I. ˈaktiv, -ēv also -əv adjective
Etymology: Middle English, from Middle French or Latin; Middle French actif, from Latin activus, from actus (past participle of agere to act) + -ivus -ive — more at agent
1. : characterized by action rather than by contemplation or speculation
an active man
2. : productive of action or movement
a dog very much awake and filled with active antagonism — Jack McLaren
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” and shone in “the sun shone” are active
— contrasted with middle and passive
b. : expressing action as distinct from mere existence or state
“he walks” and “he walked” have active verbs
— now used especially in the grammar of certain American Indian and African languages; compare neuter 1b, static , stative
c. of a grammatical construction : containing an active verb form
4. : quick in physical movement : of agile and vigorous habit : nimble , lively
an animal active in burrowing
5. : requiring vigorous action or exertion
an interest in active sports
6.
a. : having practical operation or results : effective
an active law
b. of a volcano : erupting at the present time or at intervals of a few years or having a crater that contains fluid lava — compare dormant , extinct
7.
a. : disposed to action : energetic , diligent
to take an active interest
b. : engaged in an action or activity : participating
an active club member
8. : engaged in full-time service especially in the armed forces
ordered to active duty
9. : marked by present operation, transaction, movement, or use
an active coal mine
an active bank account
active titles in a publisher's catalog
a student's active vocabulary
10.
a. : capable of acting or reacting especially in some specific manner or with more than ordinary vigor : reactive , activated
active nitrogen
active charcoal
b. : optically active
c. : radioactive
an active deposit
11. : still eligible to win the pot in poker — used of a player who has not dropped
12. : moving down the line or visiting in the set — used of couples in contredanses or square dances
13. of a disease : progressing or retrogressing
active tuberculosis
• ac·tive·ly -tə̇vlē, -li adverb
• ac·tive·ness -ivnə̇s, -ēv- also -əv- noun -es
II. noun
( -s )
1. : one that is active
fraternity alumni and actives
2.
a. : an active verb
b. : the active voice of a language or a form in it
III. adjective
1. : requiring the expenditure of energy
active calcium ion uptake
2. : of or relating to the collection, storage, and redistribution of the sun's heat especially with the aid of pumps and blowers
an active solar energy system
3. : functioning by the emission of radiant energy or sound
an active sensor
active sonar
4. : characterized by emission of large amounts of electromagnetic energy
an active galactic nucleus