Arabic nominal sentences normally have no present-tense word corresponding to English is: المكتب هادئ means “the office is quiet.” To negate that state, use the specially inflected verb ليس: ليس المكتب هادئا “the office is not quiet.” Although ليس looks and inflects like a past verb, its ordinary meaning is present-state negation.
This construction is standard contemporary MSA (formal). It is not a universal translation of English not: ليس negates a nominal predicate, while verbal events choose particles such as لا، لم، لن according to time and mood.
For the ordinary present verbal pattern, compare لا with present and habitual verbs.
The basic affirmative–negative contrast
In an affirmative nominal sentence with a noun or adjective predicate, both the subject and the predicate are nominative. With ليس, the grammatical subject—traditionally اسم ليس—remains nominative, while the predicate—خبر ليس—becomes accusative.
المكتب هادئ اليوم.
al-maktabu hādiʾuni l-yawm.
The office is quiet today.
ليس المكتب هادئا اليوم.
laysa l-maktabu hādiʾani l-yawm.
The office is not quiet today.
The overt endings in this pair expose the syntax: المكتبُ stays nominative, but هادئٌ changes to accusative هادئًا. In ordinary unvocalized writing, only the supporting alif of هادئا hints at the accusative; the vocalized reading makes the contrast explicit.
الخطة واضحة للجميع.
al-khuṭṭatu wāḍiḥatun li-l-jamīʿ.
The plan is clear to everyone.
ليست الخطة واضحة للجميع.
laysati l-khuṭṭatu wāḍiḥatan li-l-jamīʿ.
The plan is not clear to everyone.
Here ليست agrees with the feminine singular subject الخطة. English uses one invariant is not; Arabic inflects the negative copula itself.
ليس has its own inflection
The forms are irregular enough that they must be learned as a paradigm. They use the same suffix set familiar from perfect verbs, but there is no ordinary affirmative verb لاس behind them.
| Subject | Form | Meaning |
|---|---|---|
| أنا | لَسْتُ | I am not |
| أنتَ / أنتِ | لَسْتَ / لَسْتِ | you are not |
| هو / هي | لَيْسَ / لَيْسَتْ | he/it is not; she/it is not |
| نحن | لَسْنَا | we are not |
| أنتما / أنتم / أنتن | لَسْتُمَا / لَسْتُمْ / لَسْتُنَّ | you are not |
| هما m. / هما f. | لَيْسَا / لَيْسَتَا | they two are not |
| هم / هن | لَيْسُوا / لَسْنَ | they are not |
لست مسؤولا عن هذا الحساب.
lastu masʾūlan ʿan hādhā l-ḥisāb.
I am not responsible for this account. (Male speaker.)
المهندستان ليستا متاحتين هذا الأسبوع.
al-muhandisatāni laysatā mutāḥatayni hādhā l-ʾusbūʿ.
The two engineers are not available this week. (Both female.)
In the second example the subject comes first, so ليستا carries dual feminine agreement. Predicate متاحتين is accusative dual; its ـين is visible even without short vowels.
Predicate types and case
An adjective or noun predicate is accusative. A prepositional phrase or adverbial predicate has no accusative ending of its own, but it still fills the same predicate slot.
ليس المدير في المبنى الآن.
laysa l-mudīru fī l-mabnā l-ʾān.
The director is not in the building now.
هذه النسخة ليست النسخة النهائية.
hādhihi n-nuskhatu laysati n-nuskhata n-nihāʾiyya(h).
This version is not the final version.
The predicate noun النسخةَ is accusative. By contrast, في المبنى is governed internally by في; saying that it is “in the predicate position” does not change المبنى into a direct accusative noun.
Scope: what exactly is being denied?
ليس normally denies the predicate, not the existence of the subject. Corrections with بل or contrasts with لكن identify the focused constituent.
ليس الاجتماع اليوم، بل غدا.
laysa l-ijtimāʿu l-yawma, bal ghadā.
The meeting is not today, but tomorrow.
الاجتماع ليس طويلا، لكنه مهم.
al-ijtimāʿu laysa ṭawīlan, lakinnahu muhimm.
The meeting is not long, but it is important.
The first rejects the time اليوم; it does not deny that a meeting exists. The second denies only “long,” while explicitly preserving “important.” English intonation often carries this contrast; written Arabic commonly makes it explicit with بل or لكن.
Nominal negation versus verbal negation
When the predicate is an event, choose a verbal architecture instead. The final-weak verb سعى / يسعى, root س-ع-ي, makes the mood difference visible:
| Time | Architecture | Visible form |
|---|---|---|
| present/habitual | لا + indicative | لا يسعى |
| past | لم + jussive | لم يسع |
| future | لن + subjunctive | لن يسعى |
الفريق ليس مستعدا، ولم يسع إلى تأجيل التصويت.
al-farīqu laysa mustaʿiddan, wa-lam yasʿa ʾilā taʾjīli t-taṣwīt.
The team is not ready, and it did not seek to postpone the vote.
ليس مستعدا denies a state. لم يسع denies a past action and deletes final ى because لم requires the jussive. This is why one Arabic negator cannot simply replace English not everywhere.
Negative questions: بلى reverses, نعم confirms
Question hamza attaches before ليس as أليس.
أليس التقرير جاهزا للنشر؟
ʾa-laysa t-taqrīru jāhizan li-n-nashr?
Isn't the report ready for publication?
بلى، هو جاهز وسنرسله اليوم.
balā, huwa jāhizun wa-sa-nursiluhu l-yawm.
Yes, it is ready, and we will send it today. (Reverses the negation.)
نعم، ليس جاهزا بعد.
naʿam, laysa jāhizan baʿd.
That's right, it is not ready yet. (Confirms the negative proposition.)
Careful MSA organizes the answer around the proposition: بلى rejects “not ready,” while نعم accepts it. Repeating the clause prevents the ambiguity that English yes can create.
Common Mistakes
Using ما + imperfect for a present verbal clause
❌ ما يعمل النظام الآن.
Incorrect for neutral formal MSA present negation—use لا with the indicative imperfect.
✅ لا يعمل النظام الآن بسبب الصيانة.
lā yaʿmalu n-niẓāmu l-ʾāna bi-sababi ṣ-ṣiyāna(h).
The system is not working now because of maintenance.
Using لم without the jussive
❌ لم يسعى الفريق إلى حل.
Incorrect—لم requires jussive يسع, with final ى deleted.
✅ لم يسع الفريق إلى حل مؤقت.
lam yasʿa l-farīqu ʾilā ḥallin muʾaqqat.
The team did not seek a temporary solution.
Using ليس for every tense
❌ ليس وصل القطار أمس.
Incorrect—ليس does not precede a perfect verb to negate a completed event.
✅ ما وصل القطار في موعده أمس.
mā waṣala l-qiṭāru fī mawʿidihi ʾams.
The train did not arrive on time yesterday.
Keeping nūn after a mood governor
❌ الموظفون لن يرسلون النسخة اليوم.
Incorrect—لن requires the subjunctive, so masculine-plural يرسلون loses nūn.
✅ الموظفون لن يرسلوا النسخة قبل المراجعة.
al-muwaẓẓafūna lan yursilū n-nuskhata qabla l-murājaʿa(h).
The employees will not send the copy before review.
Importing English yes/no logic
❌ أليس المكتب مفتوحا؟ نعم، هو مفتوح.
Contradictory in careful MSA—نعم confirms the negative question, but the following clause reverses it.
✅ أليس المكتب مفتوحا؟ بلى، سيبقى مفتوحا حتى السادسة.
ʾa-laysa l-maktabu maftūḥan? balā, sa-yabqā maftūḥan ḥattā s-sādisa(h).
Isn't the office open? Yes, it will remain open until six.
Key Takeaways
- ليس negates a present nominal state or classification and inflects for its subject.
- Its subject remains nominative; a noun or adjective predicate is accusative.
- Prepositional and adverbial predicates fill the predicate slot without acquiring a visible accusative ending.
- Verbal events use time- and mood-sensitive negators such as لا، لم، لن.
- After a negative question, بلى reverses the negation and نعم confirms it.
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Start learning Arabic →Related Topics
- ما with the PerfectA1 — Deny completed past events with ما plus an unchanged perfect verb, and contrast this architecture with لم plus the jussive.
- لا with Present and Habitual VerbsA1 — Negate present, habitual, and general verbal clauses with لا plus the indicative imperfect, and keep this pattern distinct from prohibition.
- ما زال and Positive ContinuityA2 — Express continuing states with inflected ما زال, understanding its fossilized negative shape and kāna-like case pattern.