O.E.
stincan "emit a smell of any kind" (class III strong verb; past tense
stonc), from W.Gmc.
*stenkwanan (cf. O.S.
stincan, O.H.G.
stinkan, Du.
stinken), from the root of
stench. O.E.
swote stincan "to smell sweet," but offensive sense began O.E. and was primary by c.1250;
smell now tends the same way. Fig. meaning "be offensive" is from 1225; meaning "be inept" is recorded from 1924. The noun is attested from c.1300; sense of "extensive fuss" first recorded 1812.
Stinking in ref. to "drunk" first attested 1887;
stinking rich dates from 1956. To
stink to high heaven first recorded 1963.
Stinker as a term of abuse (often banteringly) is attested from 1607; earlier
stinkard (c.1600).
[stingk] 
,verb, stank or, often, stunk; stunk; stink⋅ing; noun 
) British Slang. chemistry as a course of study.