Definition of rat
(Entry 1 of 2)
1a
: any of numerous rodents (Rattus and related genera) differing from the related mice especially by considerably larger size
b
: any of various similar rodents
2
: a contemptible person: such as
a
: one who betrays or deserts friends or associates
b
: scab sense 3b
c
: informer sense 2
3
: a pad over which a woman's hair is arranged
4
: a person who spends much time in a specified place
a mall rat
rat
verb
ratted; ratting
Definition of rat (Entry 2 of 2)
1
: to betray, desert, or inform on one's associates
—usually used with on
2
: to catch or hunt rats
3
: to work as a scab
1
: to give (hair) the effect of greater quantity (as by use of a rat)
2
: to inform on : turn in
—usually used with out ratted out his accomplice
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Merriam-Webster unabridged
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Time Traveler for rat
The first known use of rat was before the 12th century
See more words from the same century