Incredible

google

ref

late Middle English: from Latin incredibilis, from in- ‘not’ + credibilis (see credible).

wiktionary

ref

Borrowed from Latin incrēdibilis(“that cannot be believed”), from in-(“not”) + crēdibilis(“worthy of belief”), from crēdō(“believe”).

etymonline

ref

incredible (adj.)

early 15c., "unbelievable, surpassing belief as to what is possible," from Latin incredibilis "not to be believed, extraordinary," from in- "not" (see in- (1)) + credibilis "worthy of belief" (see credible). Used c. 1400 in a now-extinct sense of "unbelieving, incredulous." Related: Incredibly; incredibility.