Some of the best kinds of parties are impromptu ones, when you decide at the last minute to get together. The adjective impromptu describes things done or said without previous thought or preparation.

Impromptu is also used as an adverb: Most people are not able to speak impromptu in front of an audience. This word was borrowed from French and ultimately derives from the Latin in prōmptū ("at hand, in readiness") from in ("in") plus a form of prōmptus ("readiness"). As you can guess from the spelling, the adjective and verb prompt are related to impromptu; they are from the same Latin verb, prōmere, "to bring forth."

Definitions of impromptu

adj with little or no preparation or forethought

“an impromptu speech”
ad-lib, extemporaneous, extemporary, extempore, off-the-cuff, offhand, offhanded, unrehearsed
without preparation; not prepared for

adv without advance preparation

n an extemporaneous speech or remark

“a witty impromptu must not sound premeditated”
Type of:
address, speech
the act of delivering a formal spoken communication to an audience

n a short musical passage that seems to have been made spontaneously without advance preparation

Type of:
musical passage, passage
a short section of a musical composition

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