Merriam-Webster Logo
  • Dictionary
  • Thesaurus
  • Medical
  • Scrabble
  • Spanish Central
  • Learner's Dictionary


adjective ac·tive \ˈak-tiv\

Simple Definition of active

  • : doing things that require physical movement and energy

  • : involved in the activities of a group or organization : participating in an action or activity

  • : involving action or participation

Full Definition of active

  1. 1 :  characterized by action rather than by contemplation or speculation <an active life>

  2. 2 :  producing or involving action or movement

  3. 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. 4 :  quick in physical movement :  lively

  5. 5 :  marked by vigorous activity :  busy <the stock market was active>

  6. 6 :  requiring vigorous action or exertion <active sports>

  7. 7 :  having practical operation or results :  effective <an active law>

  8. 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. 9 :  engaged in full-time service especially in the armed forces <active duty>

  10. 10 :  marked by present operation, transaction, movement, or use <an active account>

  11. 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. 12 :  still eligible to win the pot in poker

  13. 13 :  moving down the line :  visiting in the set —used of couples in contredanses or square dances

active noun
ac·tive·ly adverb
ac·tive·ness noun

Examples of active

  1. We stay active during the cold winter months by skiing and ice skating.

  2. We are active members of our church.

  3. While many give money to the organization, only a few are active participants.

  4. She was politically active as a volunteer for her state representative.

  5. They take an active interest in their children's education.

  6. He has taken a more active role in the production of this album.

  7. the bank's active and inactive accounts

Origin of active

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

First Known Use: 14th century

Rhymes with active

Medical Dictionary


adjective ac·tive \ˈak-tiv\

Medical Definition of active

  1. 1:  capable of acting or reacting especially in some specific way <an active enzyme> <active nitrogen>

  2. 2:  tending to progress or to cause degeneration <active tuberculosis>

  3. 3:  exhibiting optical activity

  4. 4:  requiring the expenditure of energy <active calcium ion uptake>

  5. 5:  producing active immunity <active immunization>

  6. ac·tive·ly adverb

Seen and Heard

What made you want to look up active? Please tell us where you read or heard it (including the quote, if possible).


February 7, 2016

a slight offense

Get Word of the Day daily email!


Take a 3-minute break and test your skills!


Which of the following refers to thin, bending ice, or to the act of running over such ice?

duvet pince-nez spindrift kittly-benders
Name That Thing

10 quick questions: hear them, spell them, and see how your skills compare to the crowd.


Test Your Knowledge - and learn some interesting things along the way.