This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. Prompted by the occasion rather than being planned in advance: an impromptu party.

adj. Spoken, performed, done, or composed with little or no preparation; extemporaneous: a few impromptu remarks. See Synonyms at extemporaneous.

ad. With little or no preparation; extemporaneously.

n. Something, such as a speech, that is made or done extemporaneously.

n. Music A short composition, especially for the piano, performed in an offhand or extemporized style.

adj. Improvised; without prior preparation; extemporaneous; unplanned.

n. a short musical composition for an informal occasion often with the character of improvisation and usually to be played solo.

n. any composition, musical or otherwise, that is created on the spot without preparation.

ad. Offhand; without previous study; extemporaneous; extempore.

n. Something made or done offhand, at the moment, or without previous study; an extemporaneous composition, address, or remark.

n. A piece composed or played at first thought; a composition in the style of an extempore piece.

Offhand; without previous study or preparation: as, a verse written impromptu.

Prompt; offhand; extempore; extemporized for the occasion: as, an impromptu epigram.

n. Something said or written, played, etc., at the moment, or without previous study or preparation; an extemporaneous composition or performance.

n. In music: An extemporized composition; an improvisation.

n. A composition in irregular form, as if extemporized; a fantasia.

n. an extemporaneous speech or remark

ad. without advance preparation

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

adj. with little or no preparation or forethought

"They are resourceful people and impromptu is the mode of operation they most relish."

unprepared   

speech    address    musical passage    passage   

offhand    extemporaneous    extempore   

informal    makeshift    memorable    outdoor    upcoming    annual    inaugural    elaborate    festive    grand