Derived verbs, as opposed to basic verbs, are those formed by adding some kind of verbal suffix to another word or root. The root may be verbal or non-verbal (noun or adjective). Strictly speaking, the derived verbs are not themselves a distinct verb class, but are rather a collection of similar and related verbal classes. Nevertheless it is useful to have a term for grouping grammatical features common to many types of verbs. The major classes of derived verbs are the causatives, formatives and “derivative” verbs based on adjective or noun stems (an unfortunately similarity in terminology).

Causatives: The causatives are the result of adding the causative suffixes -tā or -yā to another stem, verbal or otherwise: tul- “to come” vs. tulta- “to send for, fetch, summon, (lit.) cause to come”. Of the two suffixes, -tā is the more common. The resulting verbs are transitive (taking objects).

Formatives: The formatives are the result of adding the suffixes -t(ă) or -y(ă) to a stem, and they are most commonly used with roots which for some reason cannot be used as verbs by themselves: orya- “rise” from the root √OR “up(wards)”. The suffix -y(ă) is more common, to better differentiate the causatives and the formatives. The resulting verbs are often intransitive (unable to take objects).

Derivatives: The derivatives verbs are based on a noun or adjective. Sometimes this involves adding a suffix to the word to turn it into a verb, such as: ninque “white” → ninquita- “to whiten”. The -tā̆, -yā̆ suffixes could be used, but other suffixes were possible, such as -na. Nouns or adjectives can also be converted directly to verbs (zero-derived) if their forms are suitable, that is if they ended in the vowel -a: tengwa- “to read written matter” from tengwa “letter” (VT49/48).

The causative verbs had an especially straightforward set of conjugations, and these conjugations tended to expand into other verb classes, especially the derivative verbs based on nouns and adjectives. These are referred to as the “weak” conjugations. The formatives had more irregularities in their conjugations, especially in their past tenses, and Tolkien called them the “half-strong” verbs as a result.

It is not entirely clear whether a-verbs and u-verbs fall into the category of derived verbs, or if the added -a/-u is some sort of vocalic extension.

Neo-Quenya: Some Neo-Quenya writers (including myself at times) use the term “derived verbs” as a synonym for “weak verbs”, since the weak conjugations are very common among derived verbs. This is an oversimplification, but not too far from the truth. Another common Neo-Quenya term for this group is “a-stem verbs” since their verb stems end in a. I avoid this term myself because it is too close to the more specific a-verb class as identified by Tolkien.