1. Being in physical motion: active fish in the aquarium.
2. Functioning or capable of functioning.
3. 1. Marked by energetic activity; busy: active stock and bond markets; spent an active day sightseeing.
   2. Involving or requiring physical exertion and energy: an active workout at the gym.
   3. Being in a state of action; not quiescent: active hostilities along the border.
   4. Erupting or liable to erupt; not dormant: an active volcano.
   5. Marked by or involving direct participation: took an active interest in politics; played an active role on the committee.
   6. Currently in use or effect: an active membership.
   7. Openly acknowledged or expressed: an active dislike of the new neighbors.
   8. Indicating that the subject of the sentence is performing or causing the action expressed by the verb. Used of a verb form or voice.
   9. Expressing action rather than a state of being. Used of verbs such as run, speak, and move.
   10. Being a source of electrical energy, as a generator.
   11. Capable of converting or amplifying voltages or currents, as a diode or transistor.
4. 1. Being in a state of action; not quiescent: active hostilities along the border.
   2. Erupting or liable to erupt; not dormant: an active volcano.
   3. Marked by or involving direct participation: took an active interest in politics; played an active role on the committee.
   4. Currently in use or effect: an active membership.
   5. Openly acknowledged or expressed: an active dislike of the new neighbors.
   6. Indicating that the subject of the sentence is performing or causing the action expressed by the verb. Used of a verb form or voice.
   7. Expressing action rather than a state of being. Used of verbs such as run, speak, and move.
   8. Being a source of electrical energy, as a generator.
   9. Capable of converting or amplifying voltages or currents, as a diode or transistor.
5. 1. Marked by or involving direct participation: took an active interest in politics; played an active role on the committee.
   2. Currently in use or effect: an active membership.
   3. Openly acknowledged or expressed: an active dislike of the new neighbors.
   4. Indicating that the subject of the sentence is performing or causing the action expressed by the verb. Used of a verb form or voice.
   5. Expressing action rather than a state of being. Used of verbs such as run, speak, and move.
   6. Being a source of electrical energy, as a generator.
   7. Capable of converting or amplifying voltages or currents, as a diode or transistor.
6. Producing an intended action or effect: active ingredients.
7. Grammar
   1. Indicating that the subject of the sentence is performing or causing the action expressed by the verb. Used of a verb form or voice.
   2. Expressing action rather than a state of being. Used of verbs such as run, speak, and move.
   3. Being a source of electrical energy, as a generator.
   4. Capable of converting or amplifying voltages or currents, as a diode or transistor.
8. Producing profit, interest, or dividends: active accounts; active stocks.
9. Electronics
   1. Being a source of electrical energy, as a generator.
   2. Capable of converting or amplifying voltages or currents, as a diode or transistor.
10. Being on full military duty and receiving full pay.

1. Grammar
   1. The active voice.
   2. A construction or form in the active voice.
2. A participating member of an organization: union actives.

Synonyms: These adjectives mean engaged in activity. Active means moving, doing, or functioning: an active toddler; an active imagination; saw active service in the army.
Energetic suggests sustained enthusiastic activity: an energetic competitor.
Dynamic connotes energy and forcefulness that often inspires others: a dynamic leader.
Vigorous implies healthy strength and robustness: a vigorous crusader against drunk driving.
Lively suggests animated alertness: a lively interest in politics.