1. adj. in a state of nervous activity.

2. n. in linguistics, one of a set of forms taken by a verb to mark the relation between the time of the reported action (or state or condition) and the time of the utterance. In addition to the simple present (I run) and simple past (I ran), English has a future tense formed using the auxiliary verbs shall and will; additional aspects of the verb, expressing completed or continuous action, can be formed using the auxiliary verbs be, have, and do (I did run, I am running, etc.).