ㄹ-Stems: The Disappearing ㄹ (살다 → 삽니다, 사세요)

A whole family of common Korean verbs ends its stem in ㄹ: 살다 ("to live"), 알다 ("to know"), 만들다 ("to make"), 놀다 ("to play"), 멀다 ("to be far"), 열다 ("to open"), 팔다 ("to sell"). These stems do something that scares learners at first — their final ㄹ vanishes before certain endings — but the fear is misplaced. Unlike the seven genuinely irregular classes, the ㄹ-drop is completely predictable: it fires in front of one specific set of sounds, every single time, on every ㄹ-stem. Memorize the trigger set once and you have mastered the whole class.

The rule: ㄹ drops before ㄴ, ㅂ, ㅅ, and -(으)

The ㄹ elides when the ending begins with ㄴ, ㅂ, or ㅅ — and it also drops before the -(으) endings, where, on top of dropping, it blocks the 으 from appearing at all. A handy mnemonic: ㄹ disappears before the sounds in the nonsense word "바느실" — ㅂ, ㄴ, ㅅ — plus the -(으) set.

Notice how clean this is. In 삽니다 the ㄹ is gone and the ㅂ of the ending takes its place as the batchim; in 사세요, 사는, 사니까 the ㄹ simply drops off and the ending attaches to the now-vowel-final 사-. Watch the honorific form in the wild:

That 삽니다 is pronounced [삼니다] — the ㅂ nasalizes to [m] before the ㄴ, which is why the romanization is samnida. That is ordinary nasalization, a separate sound-change riding on top of the ㄹ-drop; don't let it distract you from the spelling rule, which is just "ㄹ out, ㅂ in."

알다 and 만들다: the same rule, every time

The reassuring thing about ㄹ-stems is their uniformity. Once you have seen 살다 do it, 알다 ("to know"), 만들다 ("to make"), 놀다 ("to play") do the identical thing:

The ㄹ stays before every other ending

Just as important as when the ㄹ drops is when it doesn't. Before endings that begin with a vowel or with any consonant other than ㄴ/ㅂ/ㅅ — most importantly the -아/어 endings and -고 — the ㄹ stays right where it is:

The one subtlety: -(으)면 keeps the ㄹ but drops the 으

The -(으) endings need a closer look, because the ㄹ and the 으 behave differently depending on the ending. Compare the "because" ending -(으)니까 with the "if" ending -(으)면:

• -(으)니까: ㄹ drops, and the 으 is blocked → 살 + (으)니까 → 사니까
• -(으)면: ㄹ stays, and only the 으 is blocked → 살 + (으)면 → 살면

Why the difference? Because -(으)니까 begins its consonant with the "ㄴ" trigger sound once the 으 is stripped away, while -(으)면 begins with ㅁ, which is not a trigger. So the ㄹ survives before 면 but falls before 니까. The one shared behavior is that a ㄹ-stem never inserts the 으 — it is already consonant-heavy enough. So you get 살면 (not ×살으면) and 사니까 (not ×살으니까). This is the single point most worth slowing down on.

Why this is elision, not irregularity

It is worth being precise about what class this is, because Korean textbooks sometimes lump ㄹ-stems in with the "irregular verbs" and terrify learners unnecessarily. The seven true irregular classes — the ㅂ, ㄷ, ㅅ, 르, 으, and ㅎ irregulars — are genuinely lexical: some verbs in each group follow the pattern and others, spelled identically, do not, so you must memorize membership verb by verb (그 verbs get their own irregular predicates group).

The ㄹ-drop is different in kind. Every stem ending in ㄹ elides in exactly the same environment; there are no ㄹ-stem exceptions to memorize. It is a phonological rule, not a lexical list — closer to English "a → an before a vowel" than to "sing → sang." That is why this page sits in the regular-stems section, next to ㄹ-irregular only as a point of contrast. Treat it as one more automatic reflex, like the 으 buffer itself, and it costs you nothing.

Reframing for English speakers

English has nothing quite like a consonant that appears and disappears depending on the next suffix, so the instinct is to see chaos. There is no chaos. Think of the ㄹ as a light that switches off in front of exactly four things — ㄴ, ㅂ, ㅅ, and the -(으) endings — and stays on everywhere else. Because the trigger set is fixed and small, and because it applies to the whole class without exception, ㄹ-stems are arguably the most predictable "irregular-looking" verbs in the language. Learn the trigger set, not a list of forms.

Common Mistakes

1. Forgetting to drop the ㄹ in the formal -ㅂ니다. The ㄹ elides; the ㅂ becomes the batchim.

2. Keeping the ㄹ before the honorific -(으)세요. ㅅ is a trigger, so the ㄹ drops.

3. Inserting the 으 buffer. ㄹ-stems never take 으; they drop the ㄹ (or keep it) instead.

4. Dropping the ㄹ before -(으)면. Here the ㄹ stays; only the 으 is blocked.

Key Takeaways

• ㄹ-stems (살다, 알다, 만들다, 놀다, 멀다) drop their ㄹ before endings starting in ㄴ, ㅂ, ㅅ and before -(으) forms: 삽니다, 사는, 사세요, 사니까.
• The ㄹ stays before -아/어 and -고: 살아요, 살고, 놀아요.
• Special case: -(으)면 keeps the ㄹ, drops the 으 → 살면 (not ×살으면, not ×사면).
• ㄹ-stems never insert the 으 buffer.
• This is a fully regular elision applying to every ㄹ-stem — not one of the seven memorize-by-verb irregular classes.