1. of alcohol or drugs.
(a) [late 17C–early 19C] sour or stale beer.
(b) [mid-19C+] plug tobacco.
(c) [mid-19C+] (US) hard cider or whisky.
(d) [1960s+] (US/N.Z. drugs) hard drugs, i.e. cocaine and heroin.
2. [mid-19C+] (UK Und., also the hard) coins (as opposed to notes).
3. [late 19C-1950s] (Und.) hard labour in prison.
4. [late 19C+] an erection [underpinned by hard-on n. (1)].
5. [1960s+] a thug, a hoodlum [hard case n. (2)].
[late 19C] of a man, to have sexual intercourse.
[19C] of a woman, to have sexual intercourse.
[1960s] of a penis, being erect.