Preverb

Although not widely accepted in linguistics, the term preverb is used in Caucasian (including all three families: Northwest Caucasian, Northeast Caucasian and Kartvelian), Caddoan, Athabaskan, and Algonquian linguistics to describe certain elements prefixed to verbs. In the context of Indo-European languages, the term is usually used for separable verb prefixes.

Theoretically, any prefix could be called a preverbal element. However, in practice, the term preverb applies more narrowly in those families and refers to a prefixed element that is normally outside the premise of verbal morphology like locations of noun elements or, less often, noun elements themselves.

In Northwest Caucasian languages, they can have nouns, directional and locative preverbs (like prepositions), like in this example from Ubykh:

In Caddoan linguistics, preverbal elements are less well defined as a class, and often, "preverb" designates a part of the verbal root that can be separated from the rest of the root by certain prefixes, as in this Wichita example:

For Mandarin Chinese and many other varieties of Chinese, the term refers to some words that carry the meanings of prepositions in English. In Chinese, they are lexically verbs and appear before the noun in question. They are more commonly referred to as coverbs.

In Georgian, a Kartvelian language, the main function of a preverb is to distinguish the present tenses and the future tenses. To turn a present tense verb into a future tense, a preverb is added to the verb compound. In addition, preverbs also have directional meanings in Georgian.

...
Wikipedia