EXTEMPORE

extemporaneous, ad-lib, extemporary, extempore, impromptu, offhand, offhanded, off-the-cuff, unrehearsed

(adjective) with little or no preparation or forethought; “his ad-lib comments showed poor judgment”; “an extemporaneous piano recital”; “an extemporary lecture”; “an extempore skit”; “an impromptu speech”; “offhand excuses”; “trying to sound offhanded and reassuring”; “an off-the-cuff toast”; “a few unrehearsed comments”

extemporarily, extemporaneously, extempore

(adverb) without prior preparation; “he spoke extemporaneously”

Source: WordNet® 3.1

Etymology

Adjective

extempore (comparative more extempore, superlative most extempore)

Carried out with no preparation; impromptu.

Adverb

extempore (comparative more extempore, superlative most extempore)

Without preparation; extemporaneously.

Noun

extempore (plural extempores)

Something improvised.

Source: Wiktionary

Ex*tem"po*re, adv. Etym: [L. ex out + tempus, temporis, time. See Temporal.]

Definition: Without previous study or meditation; without preparation; on the spur of the moment; suddenly; extemporaneously; as, to write or speak extempore. Shak.

– a.

Definition: Done or performed extempore. "Extempore dissertation." Addison. "Extempore poetry." Dryden.

– n.

Definition: Speaking or writing done extempore. [Obs.] Bp. Fell.

Source: Webster’s Unabridged Dictionary 1913 Edition