Korean verbs

A great many verbs change the pronunciation of the final consonant of the root after the addition of a suffix. Some of these changes are the result of regular consonant assimilation or cluster simplification, but some of them are irregular. The irregular verbs contain root-final consonants that were historically lenited and which, as a result disappeared or mutated between vowels but remained next to a consonant.

The lemma or citation form of a Korean verb is the form that ends in ta 다 da without a tense-aspect marker. For verbs, this form was used as an imperfect declarative form in Middle Korean,[3] but is no longer used in Modern Korean.[4] For adjectives, this form is the non-past declarative form.

Besides a verbal root itself that precedes ta in the citation form, there is also a long stem with an additional harmonic vowel, called by linguist Samuel E. Martin the "infinitive" form.[5] This tense-neutral form also does not express any honorifics and speech levels. Thus they are often used for literary titles, subtitles and chapter titles, since they are not specifically directed toward an individual or a group.[6]

This so-called infinitive, however, must not be confused with the citation form mentioned above. It is formed by attaching e⁄a 어/아 eo/a to the root, according to vowel harmony. If the verbal root ends in a vowel, the two vowels may merge or contract.

Without vowel contraction

• al 알 al "know" + e⁄a → al.a 알아 ara
• mek 먹 meok "eat" + e⁄a → mek.e 먹어 meogeo

With vowel contraction

• ka 가 ga "go" + e⁄a → ka 가 ga
• o 오 o "come" + e⁄a → wa 와 wa
• se 서 seo "stand" + e⁄a → se 서 seo'
• i 이 i (copula) + e⁄a → ye 여 yeo
• ssu 쓰 sseu "use" + e⁄a → sse 써 sseo

toy da 되다 doeda "to become" may or may not undergo contraction. ha ta 하다 hada "to do" is irregular.

This infinitive form is not used as a noun, but it can be used in compound verbs, serial verb constructions, and before certain (not all) verb endings. It may be compared to the combining stem in Japanese.

Verbs are the most complex part of speech in Korean. Their structure when used as the predicate of a clause is prefix + root + up to seven suffixes, and can be illustrated with a template:

*The negative prefix is an 안 "not"; the word mos 못 mot "cannot" also occurs in this position.

I Valency may be passive or causative. These often involve a stem change, followed by the suffix i (the spelling of this suffix may change, depending on the stem change of the verb).

II The honorific suffix is -usi 으시 -eusi- after a consonant, -si 시 after a vowel. The i ㅣ is reduced to a glide before another vowel. For example, with a following past tense, sie-ss -si-eoss- reduces to sye-ss 셨 -syeoss-.

This shows deference towards the topic of the conversation, for example when speaking of one's elders.

III If there is no suffix in this slot, the verb is in present or gnomic tense. Future tense & prospective aspect is key-ss 겠 -get-, past perfective is -e⁄a-ss 었/았 -eot-/-at but with vowel harmony. If there is no intervening consonant, this reduces, both in pronunciation and in writing: a-ss to 았 at-, and wa-ss to 왔 wat-. The verb o 오 "to come" is therefore wa-ss 왔 wat- in the perfective. The verb ha 하 ha "to do" is an irregular hay 했 hae- in the perfective.

There are also compound tenses: remote past -e⁄a-ss-e-ss 었었/았었 -eosseot-/-asseot-, past-future -e⁄a-ss-key-ss 었겠/았겠 -eotkket-/-atkket-, remote past-future (An action that should have been completed in the past but has not actually been done) -e⁄a-sse-ss-key-ss 었었겠/았었겠 -eosseotkket-/-asseotkket-

IV The formal suffix is -p ᄇ after a vowel (it is normally written in the same block as that vowel), -sup 습 -seup after a consonant in a declarative or interrogative verb, -up 읍 -eup after a consonant in a proposition. (After a consonant s or ss the ㅅ letter in the suffix drops.)

This shows deference towards the audience of the conversation, for example when speaking to one's elders. If speaking both to and of one's elders, one would use both the formal and the honorific suffixes.

V The syntactic moods, for want of a better term, are the indicative -nun 는 -neun, -ni 니, or n ㄴ; the retrospective (imperfective) -ten 던 -deon, ti 디 -di, or t ㄷ -d-; and the subjunctive si 시 -si or s ㅅ. None of these are used in the casual or intimate styles, and the formal plain indicative declarative can only occur in the gnomic tense.

-nun 는 -neun and -ten 던 -deon are used in the formal plain and familiar interrogative styles. After a vowel, -nun 는 -neun reduces to n ㄴ. Before declarative la 라 ra, -ten 던 -deon reduces to te 더 -deo.

-ni 니, -ti 디 -di, and -si 시 are used in the formal polite style.

-n ㄴ, t ㄷ -d-, and s ㅅ are used in the familiar declarative and subjunctive styles.

VI The pragmatic moods, for want of a better term, are the declarative -ta 다 -da (formal polite), -la 라 -ra (formal plain), and ey 에 -e (familiar); interrogative kka 까, ya 야 (formal) and -ka 가 -ga (familiar); propositive -ta 다 -da (formal polite), -ca 자 -ja (formal plain), and ey 에 -e (familiar); and the imperative o 오 (formal polite), -e⁄a la 어라/아라 -eola/-ala (formal plain), and -key 게 -ge (familiar).

Style: These distinctions are not made in the intimate and casual styles. Instead, this slot is taken by the intimate suffix -e⁄a 어 -eo (a 아 after an a ㅏ or o ㅗ) or the casual suffix -ci 지 -ji.

VII The polite suffix yo 요 (-i yo 이요 after a consonant) appears in the informal styles. It expresses one's relationship to the audience.

Valency in Korean is partly lexical and partly derivational. Many forms can change their valency by the addition of the passive or causative derivational suffixes, -i 이, -hi 히, -li 리 -ri, -ki 기, -wu 우 -u, -kwu 구 -gu, or -chwu 추 -chu, sometimes with additional changes to the stem.

The subject honorific suffix -(u)si derives an honorific verb, that is, a verb which is used when the subject of a sentence is higher in social status than the speaker. Such verbs are used, for example, when speaking of one's elders, one's social superiors (parents, teachers, bosses), or strangers.

The full form -usi 으시 is only used after a consonant. Otherwise, the initial vowel is absorbed, becoming -si.

While the honorific suffix is necessary, some verbs have honorific alternatives which must be used in addition to -(u)si. For instance, iss ta 있다 itda becomes kyey'si ta 계시다 gyesida.

This suffix is an enclitic consonant 'ss ㅆ after the infinitive form of the verb (ending in e⁄a), forming e⁄a'ss 았/었 (the final consonant is pronounced s͈ before a vowel and t before a consonant). This suffix, which is conventionally called "past" or "perfective" by various linguists, has many different meanings, depending on the semantics of the verb that it is attached to and the context; it may be a simple past or a present perfect.

Etymologically, 'ss is a contraction of the existential verb iss 있 via vowel absorption. The contracted form -e⁄a iss, was originally a present perfect.

A verb can superficially have two copies of the above-mentioned suffix, the second of which, however, is always -ess 었 -eot and represents a true past tense.[7] This results in the combination e⁄a'ss.ess 았었/었었 -eosseot/-asseot. This combination communicates a past perfect or a more remote past.

The future suffix is -keyss 겠 -get, often used to describe future events. It is used, when the speaker has valid reasons to believe something will be certain to happen. For instance, the suffix is used in broadcasting contexts in Korean such as weather forecasts.

But it may be used together with the perfective and pluperfect suffixes, or in a present tense context. If used with the perfective suffix, this makes an inferential or conditional past -e⁄a'ss-keyss 았겠/었겠 -eotget/-atget "should have, would have, must have." If used with the remote past suffix it makes an inferential or conditional remote past -e⁄a'ss-ess-keyss 았었겠/었었겠 -eosseotget/-asseotget, though this is rare. Because this infix is occasionally used for a conditional, or inferential tense, depending on context it is sometimes called irrealis.

Etymologically, the future suffix is the result of the merger of a resultative verb ending -key 게 and the existential root iss 있, via vowel absorption, as mentioned above. This contraction and change in meaning has its parallel in the future tense of Vulgar Latin.

The formal suffix is -(su)p ᄇ/습 -(seu)p. The short form is used after a vowel and the long form is used after a consonant. (In the Korean writing system hangul, the ㅂ is written at the bottom of the previous syllable. In South Korea, after ㅅ or ㅆ, the syllable 습 was written as 읍. This rule was modified at the end of the 80s, and 읍니다 is not the standard language. So, nowadays, the syllable 습 is written as 습 as its own pronunciation.)[8] This shows deference towards the audience of the conversation, for example when speaking in a formal situation, such as to (but not necessarily about) one's elders. If speaking both to and of one's elders, one would use the formal and the honorific suffixes together.

The syntactic moods, for want of a better term, are indicative -nun 는 -neun, -n(i) 니/ㄴ; retrospective (imperfective) -ten 던 -deon, -t(i) 디/ㄷ; and jussive -s(i)시/ㅅ.

*-ni 니, -ti 디, and -si 시 contract to -n' ㄴ, -t ㄷ, and -s' ㅅ respectively before ey 에.

None of these are used in the casual or intimate styles, and only the formal plain indicative declarative can occur in the gnomic tense.

The pragmatic moods, for want of a better term, are the declaratives ta 다, la 라, and ey 에; interrogatives kka 까, ya 야, and ka 가; propositive ta 다, -ca 자, and -ey 에; and the imperative o 오, -e⁄a la 어라/아라, and -key 게.

These distinctions are not made in the intimate and casual styles. Instead, this place is taken by the intimate suffix -e⁄a 어/아 or the casual suffix -ci 지.

The polite suffix yo 요 appears in the lower speech levels. It raises the level of politeness of those styles.