stiff (adj.) Look up stiff at Dictionary.com
Old English stif "rigid, inflexible," from Proto-Germanic *stifaz "inflexible" (cognates: Dutch stijf, Old High German stif, German steif "stiff;" Old Norse stifla "choke"), from PIE *stipos-, from root *steip- "press together, pack, cram" (cognates: Sanskrit styayate "coagulates," stima "slow;" Greek stia, stion "small stone," steibo "press together;" Latin stipare "pack down, press," stipes "post, tree trunk;" Lithuanian stipti "stiffen," stiprus "strong;" Old Church Slavonic stena "wall"). Of battles and competitions, from mid-13c.; of liquor, from 1813. To keep a stiff upper lip is attested from 1815. Related: Stiffly.
stiff (v.) Look up stiff at Dictionary.com
late 14c., "to make stiff," from stiff (adj.). Meaning "fail to tip" is from 1939, originally among restaurant and hotel workers, probably from stiff (n.), perhaps in slang sense of "corpse" (because dead men pay no tips), or from the "contemptible person" sense. Extended by 1950 to "cheat."
stiff (n.) Look up stiff at Dictionary.com
"corpse, dead body," 1859, slang, from stiff (adj.) which had been associated with notion of rigor mortis since c.1200. Meaning "working man" first recorded 1930, from earlier genitive sense of "contemptible person," but sometimes merely "man, fellow" (1882). Slang meaning "something or someone bound to lose" is 1890 (originally of racehorses), from notion of "corpse."