Etymology: Middle English, from Anglo-French or Latin; Anglo-French actif, from Latin activus, from actus, past participle of agere to drive, do — more at agent
Date: 14th century
1. characterized by action rather than by contemplation or speculation <an active life> 2. producing or involving action or movement 3. a. of a verb form or voice asserting that the person or thing represented by the grammatical subject performs the action represented by the verb <hits in “he hits the ball” is active> b. expressing action as distinct from mere existence or state 4. quick in physical movement ; lively 5. marked by vigorous activity ; busy <the stock market was active> 6. requiring vigorous action or exertion <active sports> 7. having practical operation or results ; effective <an active law> 8. a. disposed to action ; energetic <took an active interest> b. engaged in an action or activity <an active club member> c. of a volcano currently erupting or likely to erupt — compare dormant 2a, extinct 1b d. characterized by emission of large amounts of electromagnetic energy <an active galactic nucleus> 9. engaged in full-time service especially in the armed forces <active duty> 10. marked by present operation, transaction, movement, or use <an active account> 11. a. capable of acting or reacting ; reacting readily <active nitrogen> <active ingredients> b. tending to progress or to cause degeneration <active tuberculosis> c. of an electronic circuit element capable of controlling voltages or currents d. (1) requiring the expenditure of energy <active calcium ion uptake> (2) functioning by the emission of radiant energy or sound <radar is an active sensor> 12. still eligible to win the pot in poker 13. moving down the line ; visiting in the set — used of couples in contredanses or square dances • active noun • actively adverb • activeness noun
New Collegiate Dictionary. 2001.