starch (n.) Look up starch at
"pasty substance used to stiffen cloth," mid-15c., back-formation from starch (v.). Figurative sense of "stiffness of manner" is recorded from 1705.
starch (v.) Look up starch at
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 *starkjan "to make hard" (source also of German Stärke "strength, starch," Swedish stärka "to starch"), from PIE root *ster- (1) "stiff." Related: Starched; starching.