'autoschediastic' originates from Greek, specifically the elements 'autos' and 'schediastikos' (from 'schedia'), where 'autos' meant 'self' and 'schedia' meant 'a plan, an expedient' (hence something devised).

'autoschediastic' was formed in Modern English as a learned formation from New/Neo-Latin or Late Greek 'autoschediastikos' (from Greek 'autos' + 'schediastikos'), entering English usage as an adjective in the 19th century to describe things made or done on the spot.

Initially it meant 'made or devised for the occasion' and over time has retained the core sense of 'improvised' or 'extemporaneous' with little semantic shift.