–adjective
1. engaged in action; characterized by energetic work, participation, etc.; busy: an active life.
2. being in a state of existence, progress, or motion: active hostilities.
3. involving physical effort and action: active sports.
4. having the power of quick motion; nimble: active as a gazelle.
5. characterized by action, motion, volume, use, participation, etc.: an active market in wheat; an active list of subscribers.
6. causing activity or change; capable of exerting influence (opposed to passive): active treason.
7. effective (opposed to inert): active ingredients.
8. Grammar. noting or pertaining to a voice of verbal inflection in which typically the subject of the sentence is represented as performing the action expressed by the verb (opposed to passive): Writes in He writes a letter every day is an active verb form.
9. requiring or giving rise to action; practical: an active course.
10. (of a volcano) in eruption.
11. Accounting. profitable; busy: active accounts.
12. requiring personal effort or attention; not automatic: an active alarm system.
13. interest-bearing: active paper.
14. Medicine/Medical. acting quickly; producing immediate effects: active remedies.
15. Sociology. (of a crowd) engaging in purposeful activity, often of a militant nature. Compare expressive (def. 4).
16. Aerospace. able to transmit signals: an active communications satellite.
17. Electronics. (of a device or system) acting as a source of electrical energy, as a generator, or capable of amplifying or converting voltages or currents, as a transistor or diode.
18. (of a solar heating system) accumulating and distributing solar heat by mechanical means.
19. Military. serving on active duty.
