keenly watchful to detect danger; wary: a vigilant sentry.
ever awake and alert; sleeplessly watchful.

Origin of vigilant

1470–80; < Latin vigilant- (stem of vigilāns), present participle of vigilāre to be watchful. See vigil, -ant
Related formsvig·i·lant·ly, adverbvig·i·lant·ness, nounhy·per·vig·i·lant, adjectivehy·per·vig·i·lant·ly, adverbhy·per·vig·i·lant·ness, nounnon·vig·i·lant, adjectivenon·vig·i·lant·ly, adverbnon·vig·i·lant·ness, nounpre·vig·i·lant, adjectivepre·vig·i·lant·ly, adverbsu·per·vig·i·lant, adjectivesu·per·vig·i·lant·ly, adverbun·vig·i·lant, adjectiveun·vig·i·lant·ly, adverb
Can be confusedvigilant vigilante

Synonyms for vigilant

Synonym study

2. See alert.

Antonyms for vigilant Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for vigilant

Contemporary Examples of vigilant

Historical Examples of vigilant

British Dictionary definitions for vigilant



keenly alert to or heedful of trouble or danger, as while others are sleeping or unsuspicious
Derived Formsvigilantly, adverbvigilantness, noun

Word Origin for vigilant

C15: from Latin vigilāns keeping awake, from vigilāre to be watchful; see vigil
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 vigilant

late 15c., from Latin vigilantia "wakefulness," from vigilia (see vigil). Related: Vigilantly.

Online Etymology Dictionary, © 2010 Douglas Harper