Stems of a Verb

Persian verbs have two simple stems and one compound stem. The simple stems are “past stem” and “present stem”. Old Persian has several compound stems but modern Persian has only one compound stem called “causative stem”. Verbal stems are used in conjugating verbs, making participles and also, in word formation. For example, past stem is used to conjugate verbs in perfective past tense and present stem is used to conjugate verbs in perfective present tense.

Past stem

The past stem of a verb is obtained by removing “-an” from its infinitive form.

Present stem

In Old Persian, verbs have various stems that derive from the same root. For example, by adding “-a” to the root “bar” (to take), we get the present stem “bara” and by converting the root to its weak form i.e. “bərə” and adding “-ta” to it, we get the past stem “bərəta”. The relation between a root and its stems has been lost in the transition of Old Persian to Middle Persian and New Persian. Therefore, there is no general rule to obtain the present stem of a verb from its infinitive form. Knowing about verb formation and classification of irregular verbs can help you in learning and memorizing present stems.

It should be noted that each verb whether regular or irregular, has one and only one present stem for all persons. Therefore, as opposed to languages like French and Spanish, Persian does not have irregular conjugations. The following table shows the conjugation of دیدن (didan: to see) in present tense. Its present stem بین (bin) is irregular but its conjugation is regular:

Indirect rule

There is a regular rule for obtaining the present stem of a verb but it is mainly useful for native speakers:

1. Consider the imperative form of the verb for second-person singular
2. Drop the prefix ب (it could be pronounced “be”, “bi” or “bo”)
3. Drop the epenthetic consonant “-y-” (if it exists)
4. If it ends with “-ow”, change it to “-av”

Examples:

Causative stem

The causative stem of a verb is obtained by adding “-ân” to its present stem. Not all verbs have a causative stem. It is formed only for verbs that can have a causative meaning.