A verb is a word that expresses an action, an event, or a state of being about the subject.
ASL linguists describes three major types of verbs: plain verbs, indicating verbs (including directional verbs, reciprocal verbs, locative verbs), and depicting verbs (including classifier predicates).
Not all ASL verbs can be inflected to indicate the subject and the object in a sentence. They are called "plain verbs". They require the signer to specify the subject and the object (e.g. pronouns and nouns) before and/or after the verb.
For example, the ASL verb understand is a plain verb that the signer cannot inflect it in a sentence. The signer has to specify the subject and the object in a sentence, for example: I understand you.
Some examples of the plain verbs that cannot be inflected are as follows:
eat, enjoy, know, love, remember, understand, have, cherish ...
The plain verbs are a small set of verbs that cannot be modulated. But, the majority of ASL verbs can be inflected into many different ways to contain information about the subject and the object.
The indicating verbs are modulated verbs by inflecting the direction or movement of the regular ASL verbs to indicate the subject and the object in a sentence.
The following verbs are some examples that can be modulated to contain the information about the subject and the object.
inform, give, distribute ...
Another category of ASL verbs is depicting verbs. Many of these verbs are known as "classifier predicates". Depicting verbs contain information about the action or state of being. Here are some examples:
vehicle-drive-by, person-walk-awkwardly, pencil-roll-down-stairs ...
Clayton Valli, et al. "Linguistics of American Sign Language: An Introduction." Washington, D.C.: Gallaudet University Press. 2005. Pp 76-82.
Charlotte Haker-Shenk and Dennis Cokely. "American Sign Language: A Teacher's Resource Text on Grammar and Culture." Washington, D.C.: Gallaudet Press. 1980.
Learn why there are no to-be verbs in sign language.
Indicating verbs in sign language.
Depicting verbs (classifier predicates).
Understand the difference in movement for noun-verb pairs.
You may be also interested in agent-action construction in sign language linguistics.