Learners meet ש־, כי and אשר as three translations of English that and try to choose between them by feel. That is the wrong shape for the problem. They are not three interchangeable words with different politeness levels — they have different grammar, and once you can state what each one can and cannot do, most of the choosing disappears. The quick mid-sentence decision procedure lives on ש־, כי or אשר?; this page is the anatomy behind it.
Start with the shape of the word
ש־ is a prefix. It has no independent existence: it is welded to the first word of its clause, like ה־ or ב־. כי and אשר are free words with a space on both sides. That one difference has consequences all the way down, including which of them can build compound connectives and how.
| ש־ | כי | אשר | |
|---|---|---|---|
| written attached to the next word | yes | no | no |
| complement clause (that) | yes, every register | yes, formal and journalistic | no |
| relative clause (who, which) | yes, every register | no | yes, formal and literary |
| causal clause (because) | no | yes, every register | no |
| builds compounds with a preposition | אחרי ש־, כדי ש־, כש־ | no | כאשר, באשר, מאשר |
The bottom row is the one nobody points out. ש־ and אשר both build connectives out of a preposition; כי builds none, which is why it can never be swapped into a compound — there is nothing to swap it into. That is not the same as saying כי never pairs with another particle: כי אם but rather and אף כי although are both alive in formal writing, and אף כי returns 2,403 on Hebrew Wikipedia in ordinary encyclopedic prose. But those are frozen pairs to recognise, not a pattern that extends, and neither is built on a preposition. The everyday concessive that does use כי, אם כי, is on אם.
לא הזמנתי כרטיסים כי חשבתי שאתם לא באים.
lo hizmánti kartisím ki khashávti she'atém lo ba'ím
I didn't book tickets because I thought you weren't coming. (both words in one sentence, each doing its own job)
Why there are three of them at all
The arrangement is a historical layering, and seeing it makes the register facts stop feeling arbitrary. אשר is the relative of Biblical Hebrew. ש־ is the relative that dominates the Mishnah and rabbinic Hebrew and became the ordinary modern form — which is also why it ended up a prefix, since a word used that often wears down onto the next one. כי is Biblical in both of its senses, the causal one and the content-clause one, and it is the second of those that survives today as a marker of formal register.
Nothing in that sequence was retired. Modern Hebrew keeps all three in service and sorts them by how formal the sentence is — which is why a rule of the form "use X, not Y" is the wrong shape for this problem.
Measured: כי and אשר barely overlap
Counted on Hebrew Wikipedia's article namespace with the regex form of insource: on 17 August 2026, with the same probe shape — one space on each side — down every column, so that the two words are caught by the same net.
| Frame | with כי | with אשר |
|---|---|---|
| after a reporting verb — אמר amár | 2,685–3,107 | 3 |
| on a noun — האיש ha'ísh | 8 | 68 |
Now read the hits, because the raw figures understate the split in both directions. None of the three אמר אשר hits is the construction: two are quotations of a biblical verse inside rabbinic prose, and the third is the pop singer Usher, whose name is written אשר in Hebrew. And all eight האיש כי hits are the same non-instance: כי opens a complement clause, and האיש belongs to the material in front of it — הודה האיש כי, סיפר האיש כי, חשף האיש כי. Not one is a relative clause.
So the distribution is cleaner than the table looks: כי complements and does not relativise; אשר relativises and does not complement; ש־ does both.
insource: abandons common strings under load, so it drifts between runs, which is why it is printed as the band three consecutive runs actually returned. The three small figures reproduced identically across the same three runs — and are small enough to read. And the one column that cannot be measured this way is ש־ itself: it is a prefix, so אמר שהוא is a two-word string and no phrase search can isolate it. The ratio of אמר כי to אמר ש־ has been measured once, by pinning the pronoun that follows, on ש־, כי or אשר? — close to a third of the that-clauses after אמר are built with כי.הוא טען שלא קיבל שום מכתב.
hu ta'án sheló kibél shum mikhtáv
He claimed he never got any letter. (everyday)
הוא טען כי לא קיבל שום מכתב.
hu ta'án ki lo kibél shum mikhtáv
He claimed that he had received no letter. (formal and journalistic — same claim, one word changed)
What the evidence cannot tell you: register
Milog has no register field, and where it does state a register it does so inside the gloss — its ברם entry opens מילת קישור ספרותית. It says nothing of the kind about ש־, כי or אשר. So nothing in the dictionary establishes that אשר is formal, and asserting it as a dictionary fact would be inventing a source. It has to be shown from where the word actually appears, and it appears in a narrow and recognisable set of places: statute and contract, official correspondence, liturgy (the blessing formula אשר קידשנו במצוותיו), memorial and dedication inscriptions, and poetry. It does not appear in a text message.
That is a fact about habitat, not about grammar: the Academy of the Hebrew Language's decision 4.5א names ש and אשר as the two relative markers and assigns no division of labour between them at all.
כל אדם אשר נפגע מן ההחלטה רשאי להגיש ערעור.
kol adám ashér nifgá min hahakhlatá rashái lehagísh ir'úr
Any person adversely affected by the decision may lodge an appeal. (formal — statute, rulings, letters from an authority)
כל מי שנפגע מההחלטה יכול להגיש ערעור.
kol mi shenifgá mehahakhlatá yakhól lehagísh ir'úr
Anyone who's been hurt by the decision can appeal. (the same content in ordinary Hebrew)
העובד יחזיר כל ציוד אשר קיבל מן החברה.
ha'ovéd yakhazír kol tsiyúd ashér kibél min hakhevrá
The employee shall return any equipment received from the company. (contract Hebrew)
The compounds, and one that is not one
BDB lists the preposition-plus-אשר compounds as באשר, כאשר and מאשר. All three are alive in modern Hebrew, and only one of them is a style choice: כאשר has an everyday twin in כש־, while באשר ל־ and מאשר have no ש־ form at all. This is why every learner is already using אשר daily without noticing — every comparative than is מאשר.
עדיף לצאת עכשיו מאשר להיתקע בפקק בשש.
adíf latsét akhsháv me'ashér lehitaká bapkák beshésh
Better to leave now than get stuck in traffic at six. (everyday — and it is the same אשר)
מאחר ש־ looks like a fourth member and is not one. Jastrow files מאחר under אַחַר, as a conjunction taking ש־ or Aramaic ד־, and the Academy's dictionary glosses מאחר ש־ as לפי, מכיוון. The mis-parse is easy to make from the spelling alone, and it has a production consequence: there is no אשר form. insource:/ מאחר אשר / returns 0, as does insource:/ למרות אשר /, against 931–938 for the identically shaped insource:/ מאחר שהוא /.
מאחר שהמועד חלף, הבקשה לא תידון.
me'akhár shehamo'éd khaláf, habakashá lo tidón
Since the deadline has passed, the request will not be considered. (formal)
Common Mistakes
1. Reaching for כי as the everyday that. Both of the following are ✅ — that is exactly the point. What differs is who is speaking, and a learner who uses the first one across a café table sounds like a news presenter.
נמסר כי השביתה תסתיים בחצות.
nimsár ki hashvitá tistayém bakhatsót
It has been announced that the strike will end at midnight. (formal and journalistic)
שמעתי ברדיו שהשביתה נגמרת בחצות.
shamáti barádyo shehashvitá nigméret bakhatsót
I heard on the radio that the strike ends at midnight. (what you would actually say)
2. Using ש־ for because. The mirror image of the first error, and it comes from the same place: one English word covering two Hebrew jobs. ש־ hooks a clause onto a verb or a noun; it does not supply a reason.
❌ לא הלכתי לעבודה שהיה לי חום
Incorrect — ש־ does not head a causal clause in Modern Hebrew. 'Because' is כי, or בגלל ש־: לא הלכתי לעבודה כי היה לי חום.
✅ לא הלכתי לעבודה כי היה לי חום כל הלילה.
lo halákhti la'avodá ki hayá li khom kol haláyla
I didn't go to work because I had a fever all night.
3. Using אשר to open a complement clause. Once אשר is filed as "formal that", it wants to follow a verb. It cannot: אשר attaches a clause to a noun, never to a verb, which is why the corpus probe for it comes back empty.
❌ הרופאה אמרה אשר הבדיקה תקינה
Incorrect — אשר attaches a clause to a noun and never to a verb, so it cannot open a complement clause. Use ש in speech or כי in formal writing: הרופאה אמרה שהבדיקה תקינה.
✅ הרופאה אמרה שהבדיקה תקינה ואין מה לדאוג.
harof'á amrá shehabdiká tkiná ve'éin ma lid'óg
The doctor said the test was fine and there's nothing to worry about. (f. doctor)
4. Upgrading every ש־ to אשר to sound educated. The compounds are fixed: מאחר and למרות take ש־ and have no אשר form, so the upgrade produces a word that does not exist.
❌ מאחר אשר לא הגשת את הטופס, הבקשה נדחתה
Incorrect — מאחר is not built on אשר and has no אשר form; it takes ש־. Both מאחר אשר and למרות אשר return zero on Hebrew Wikipedia. Write מאחר שלא הגשת את הטופס.
✅ מאחר שלא הגשת את הטופס בזמן, הבקשה נדחתה.
me'akhár sheló higáshta et hatófes bazmán, habakashá nidkhatá
Since you didn't submit the form on time, the request was turned down. (to a man — formal)
Key Takeaways
- The three differ in grammar, not politeness: ש־ is a bound prefix, כי and אשר are free words.
- ש־ does both jobs — complement and relative — in every register, and is never the wrong answer.
- כי complements and causes; it does not relativise. All eight האיש כי hits on Hebrew Wikipedia open a complement clause, and not one of them is a relative.
- אשר relativises; it does not complement. אמר אשר returns three hits: two biblical quotations and the singer Usher.
- Milog has no register field and labels only inside the gloss, so אשר's formality is shown by habitat — statute, contract, liturgy, inscription, poetry — and the Academy's decision 4.5א treats ש and אשר as equal relative markers.
- The אשר compounds are באשר, כאשר, מאשר (BDB). כאשר has an everyday twin in כש־; the other two have none, so they are not style choices.
- מאחר ש־ is not an אשר compound — Jastrow files it under אַחַר — and מאחר אשר returns zero.
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Start learning Hebrew →Related Topics
- ש־, כי or אשר?B1 — English says that for four different jobs, and Hebrew splits them across a prefix, a causal word that is also a complementiser, and a relative that careful writing still uses. The register facts here get turned into false errors constantly — אמר כי is standard formal Hebrew and אשר is a live literary choice, not a mistake.
- אשר: The Formal RelativeC1 — אשר is the free-standing relative marker familiar from legal language, ceremonial prose, the Tanakh and elevated journalism. It normally changes register rather than meaning, while compounds such as כאשר, באשר ל־, אשר על כן and מאשר have developed lives of their own.
- ש־: The Universal SubordinatorA2 — One attached letter does the work English splits across that, which, who and when: אמרתי שאני בא, החבר שהמליץ לי, ביום שהגענו. It is a prefix rather than a word, it is never optional, and it is the building block of אחרי ש־, לפני ש־, כדי ש־, למרות ש־ and the rest of the connective family — most of which have a bare twin that takes a noun instead of a clause.
- כי: BecauseA2 — כי is the everyday word for because — the natural answer to למה and the ordinary way to attach a reason mid-sentence, as in לא עניתי לך כי הטלפון היה על שקט. It is also a second thing that courses leave out: a complementiser meaning that, which is why נמסר כי and הודיע כי are standard news Hebrew rather than mistakes.