AUTOSCHEDIASTIC

Adjective

autoschediastic (comparative more autoschediastic, superlative most autoschediastic)

(dated) impromptu, ex tempore or offhand

Source: Wiktionary

Au`to*sche`di*as"tic, Au`to*sche`di*as"tic*al, a. Etym: [Auto- + Gr. Schediasm.]

Definition: Extemporary; offhand. [R.] Dean Martin.

Source: Webster’s Unabridged Dictionary 1913 Edition