late 14c., from Old English *stercan (Mercian), *stiercan (West Saxon) "make rigid," found in stercedferhð "fixed, hard, resolute" (related to stearc "stiff"), from Proto-Germanic *starkijan "to make hard" (cognates: German Stärke "strength, starch," Swedish stärka "to starch"), from PIE root *ster- (1) "strong, firm, stiff, rigid" (see stark). Related: Starched; starching.

"pasty substance used to stiffen cloth," mid-15c., back-formation from starch, v.. Figurative sense of "stiffness of manner" is recorded from 1705.