[verb ob-li-geyt; adjective ob-li-git, -geyt]
verb (used with object), ob·li·gat·ed, ob·li·gat·ing.
  1. to bind or oblige morally or legally: to obligate oneself to purchase a building.
  2. to pledge, commit, or bind (funds, property, etc.) to meet an obligation.
  1. morally or legally bound; obliged; constrained.
  2. necessary; essential.
  3. Biology. restricted to a particular condition of life, as certain organisms that can survive only in the absence of oxygen: obligate anaerobe (opposed to facultative).

Origin of obligate

1400–50; late Middle English obligat (adj.) < Latin obligātus (past participle of obligāre to bind), equivalent to ob- ob- + ligātus; see ligate
Related formsob·li·ga·ble [ob-li-guh-buh l] /ˈɒb lɪ gə bəl/, adjectiveob·li·ga·tor, nounnon·ob·li·gat·ed, adjectivepre·ob·li·gate, verb (used with object), pre·ob·li·gat·ed, pre·ob·li·gat·ing.qua·si-ob·li·gat·ed, adjectivere·ob·li·gate, verb (used with object), re·ob·li·gat·ed, re·ob·li·gat·ing.un·ob·li·gat·ed, adjective
Can be confusedobligate oblige
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for obligator


  1. to compel, constrain, or oblige morally or legally
  2. (in the US) to bind (property, funds, etc) as security
  1. compelled, bound, or restricted
  2. biology able to exist under only one set of environmental conditionsan obligate parasite cannot live independently of its host Compare facultative (def. 4)
Derived Formsobligable, adjectiveobligative, adjectiveobligator, noun

Word Origin for obligate

C16: from Latin obligāre to oblige
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for obligator



1540s, "to bind, connect;" 1660s, "to put under moral obligation," back-formation from obligation, or else from Latin obligatus, past participle of obligare (see oblige). Oblige, with which it has been confused since late 17c., means "to do one a favor." Related: Obligated; obligating.

Online Etymology Dictionary, © 2010 Douglas Harper

obligator in Medicine


[ŏblĭ-gĭt, -gāt′]
  1. Able to exist or survive only in a particular environment or by assuming a particular role.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

obligator in Science


[ŏblĭ-gĭt, -gāt′]
  1. Capable of existing only in a particular environment or by assuming a particular role. An obligate aerobe, such as certain bacteria, can live only in the presence of oxygen. An obligate parasite cannot survive independently of its host. Compare facultative.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.