Aspect in depth

After this page you will be able to explain the difference between imperfective and perfective verbs, recognise the main ways aspect pairs are formed, and know which forms each kind of verb has in the present, past and future. You will also have rules of thumb for choosing the right verb: for a single completed action, a repeated action, an action that lasts, a negative sentence, and after verbs such as start and finish.

The past tense and the future tense introduced aspect. This page brings it together.

Two ways of seeing an action

Most Ukrainian verbs come in pairs that share one English translation [src: ukma-ukrainian-foreign-language]:

• the imperfective verb (недоко́наний вид) looks at the action as a process, or as something repeated. Whether it was finished is not the point;
• the perfective verb (доко́наний вид) looks at the action as one whole, completed, usually with a result.

The English translation does not always show the difference. I wrote a letter can translate either sentence, depending on what the speaker wants to stress.

How pairs are formed

There is no single rule that turns one aspect into the other. Learn each verb with its partner. Most pairs follow one of three patterns.

A prefix makes the perfective

Many perfectives are the imperfective verb with a prefix. Which prefix is used has to be learned with the verb.

A prefix can also change the meaning, so not every prefixed verb is the plain partner of the simple verb. Записа́ти, for example, means “to write down, to record”, not just “to write”.

A change of suffix

In other pairs the two verbs share a root but have different suffixes. Often the imperfective is the longer verb, and the stress may move.

Different words

A few common pairs use entirely different stems. These are standard pairs in textbooks, but in the dictionary each verb has its own entry, so learn them as items.

Говори́ти also means “to speak, to talk”, while сказа́ти means only “to say, to tell”.

Aspect in each tense

Both kinds of verb have an infinitive and a past tense. The difference is in the present and the future [src: ukma-ukrainian-foreign-language].

• No perfective present. An action that is still going on cannot be seen as completed, so perfective verbs have no present tense [src: ukma-ukrainian-foreign-language]. Aspect also matters in commands; see The imperative.
• Perfective future. The forms of a perfective verb that look like the present tense mean the future: напишу́ is I will write, not I write. See the future tense.
• Imperfective future. Imperfective verbs make the future with бу́ду + infinitive, or with the one-word form писа́тиму. Perfective verbs never use бу́ду.

Choosing the aspect

These are tendencies, not mechanical rules. Native speakers choose by what they want to say, and sometimes both verbs are possible with a small change of meaning.

One completed action: perfective

Use a perfective verb for a single action that is (or will be) completed, especially when the result matters, and for a sequence of actions where each one finishes before the next begins.

Repeated or habitual actions: imperfective

Use an imperfective verb for actions that happen regularly or many times. Words such as завжди (always), ча́сто (often), щодня́ (every day) and щоро́ку (every year) usually go with an imperfective verb.

Compare a single occasion with the perfective: Учо́ра вона́ забу́ла ключі́. (Yesterday she forgot her keys.)

Duration: imperfective

When you say how long an action went on, or describe what was happening at a moment, use an imperfective verb.

Questions about the action itself

When you ask whether an action has ever happened, or just name the activity without caring about the result, the imperfective is common. This is a tendency, and a perfective question is also possible when you ask about a result.

Negation

In negative sentences the imperfective often means that the action did not happen at all, while the perfective often means that an expected result was not reached. Again, treat this as a tendency. See also negation.

After “start”, “finish” and “stop”: imperfective infinitive

Verbs meaning start, finish and stop are followed by an imperfective infinitive, because they describe a stage of a process. The verbs themselves have both aspects: почина́ти / поча́ти (to start), закі́нчувати / закінчити (to finish) and перестава́ти / переста́ти (to stop).

Закінчити is left without a stress mark on this page: the dictionary accepts two stresses, закі́нчити and закінчи́ти, and the same goes for its past forms.

How dictionaries mark aspect

Dictionaries label every verb. Горох shows the label on the word-forms page: недоко́наний вид (imperfective) or доко́наний вид (perfective). The definitions page (from the academic dictionary СУМ) uses the abbreviations недок. and док. and often points from one verb to its partner: написа́ти is defined as “Док. до писа́ти”, the perfective of писа́ти [src: goroh-dictionary].

The dictionary sometimes pairs a perfective with a longer imperfective rather than the one you learnt first. For прочита́ти it gives прочи́тувати, and for ви́пити it gives випива́ти [src: goroh-dictionary]. In everyday use, чита́ти / прочита́ти works as a pair, as on the future tense page.

Summary

Common mistakes and limits