The verbal morphology of Armenian is complicated by the existence of two main dialects, Eastern and Western. The following sketch will be a comparative look at both dialects.
Non-finite forms
Infinitive
The infinitive of Armenian verbs is formed with the stem, the theme vowel, and the affix -լ (-l).
The endings reflect the number of conjugations possible. Western Armenian is conservative, retaining three conjugations in a, e, and i, while Eastern Armenian has collapsed I and II:
Stems
There are two main stems per verb, the present stem and past stem. For conjugations I/II, the past stem is identical to the present stem, which is basically the verb minus the theme vowel and ending:
The augment for the third conjugation is sometimes in -եց (-ec῾).
Participles
The number and type of participles varies by dialect.
Future participle
Both Eastern and Western Armenian form the common future participle in -լու (-lu). Western Armenian has one additional future participle in -լիք (-lik῾):
Present and past participles
Present
Eastern Armenian has three present participles, while Western Armenian has one. The two exclusively Eastern present participles are in -ում (-um) (for all verb classes) and -լիս (-lis); both affixes attach to the present stem. Eastern and Western Armenian have a common present participle -ող (-oġ), which attaches to the past stem; it is sometimes used as an agentive noun: ուսանող (usanoġ student) [fr. ուսանել usanel to study)].
Past
All affixes here attach to the past stem. Both dialects have a common past passive participle in -ած (WA -aj/EA -ac). Where the dialects differ is the past active participle. The Western Armenian participle is -եր (-er) for all conjugations, while Eastern Armenian has -ել (-el).
Finite forms
Introduction: general overview
Armenian features within its verbal system a system that encodes person and number, as well as tense, mood, and aspect (see following section for more.)
Armenian inherited from Indo-European two sets of synthetic affixes corresponding roughly to a "present" or general series, and a past series:
How these affixes are used varies between the two modern dialects of Armenian.
Tense/mood/aspect
Both dialects have five moods: indicative, conditional, optative/subjunctive, necessitative, imperative; of these only the imperative has no tense distinction. The number of tenses varies by dialect. Aspect is divided roughly the same in both dialects, but the distribution is slightly different.
Indicative mood
Both Eastern and Western feature one present, one future, and two past tenses (imperfect, preterite). Their formation varies by dialect.
Present
Formation of the present tense differs between Eastern and Western. In form, the present indicative of Eastern Armenian has no corresponding Western formation. However, the Western present indicative is formed identically to the Eastern present conditional.
Eastern Armenian uses the -ում (-um) participle with the present tense of Eastern Armenian verb լինել (linel "to be"). Western Armenian uses a synthetic general form of the verb preceded by the particle կը gë /gə/. The synthetic form conjugates according to the verb's theme vowel (i.e., e, i, or a).
In Armenian, final /j/ in polysyllabic words is silent.
Imperfect
The formation of the imperfect is similar to the present-tense formation in both dialects. Eastern Armenian uses the -ում (-um) participle with the imperfect of verb լինել (linel "to be"). Western Armenian uses a synthetic imperfect form of the verb preceded by the particle կը gë /gə/.
Note that in all forms, Eastern and Western, that feature the combination էի (e.g., սիրում էիմ/կը սիրէիմ, etc.), there is an epenthetic yod: sirum ēi or ; gë sirēi .
Future
Like the formation of the present tense, the future tense in Armenian intersects two varying constructions with opposite meanings. The Eastern future tense is made with the future participle in -լու (-lu) with the present tense of verb լինել (linel). (This Eastern form is identical to the Western Armenian non-past necessitative (see below.)) The Western future tense is made with the general synthetic verb preceded by the particle պիտի (bidi). (This Western form is identical to the Eastern Armenian non-past necessitative (see below.))
Note that in all Eastern forms that feature the combination ու + ե (e.g., կարդալու եմ, etc.), epenthetic yod appears: kardalu em or .