Definition of boo
(Entry 1 of 4)
—used to express contempt or disapproval or to startle or frighten
boo
noun (1)
plural boos
Definition of boo (Entry 2 of 4)
1
: a shout of disapproval or contempt
2
: any utterance at all
—usually used in negative constructions never said boo
boo
verb
booed; booing; boos
Definition of boo (Entry 3 of 4)
: to deride especially by uttering a prolonged boo
: to express disapproval of by booing
the crowd booed the referee
boo
noun (2)
plural boos
Definition of boo (Entry 4 of 4)
US slang
: a romantic partner : sweetheart, honey
Your parents might keep a sharp eye on potential partners and your besties may lay down difficult "friend tests," but only one real opinion on your new boo truly matters: what your dog thinks of them.— Jaime Lees This has left me skeptical of all new relationships—including my new boo.— Griffin Wynne
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Merriam-Webster unabridged
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Time Traveler for boo
The first known use of boo was in 1639
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