ac·tive / ˈaktiv/ • adj. 1. (of a person) engaging or ready to engage in physically energetic pursuits. ∎  moving or tending to move about vigorously or frequently: active fish need a larger tank. ∎  characterized by energetic activity: they enjoyed an active social life. ∎  (of a person's mind or imagination) alert and lively.2. doing things for an organization, cause, or campaign, rather than simply giving it one's support. she was active in the affairs of the institute. ∎  (of a person) participating or engaged in a particular sphere or activity: a politically active student body. ∎  (of a person or animal) pursuing their usual occupation or activity, typically at a particular place or time: tigers are active mainly at night.3. working; operative: the mill was active until 1960. ∎  (of a bank account) in continuous use. ∎  (of an electrical circuit) capable of modifying its state or characteristics automatically in response to input or feedback. ∎  (of a volcano) currently erupting, or that has erupted within historical times. Often contrasted with dormant or extinct. ∎  (of a disease) in which the symptoms are manifest; not in remission or latent. ∎  having a chemical or biological effect on something: 350 active ingredients have been banned from pesticides.4. Gram. relating to or denoting the voice that attributes the action of a verb to the person or thing from which it logically proceeds (e.g., of the verbs in guns kill and we saw him). The opposite of passive.• n. Gram. an active form of a verb. ∎  (the active) the active voice.DERIVATIVES: ac·tive·ly adv.

ACTIVE (VOICE). See PASSIVE (VOICE), VERB, VOICE.

active Another term for running.