1. [late 17C–19C] a full glass, esp. when raised in a toast; also as v., to make a toast; thus bumpering n., drinking, bumper, to drink ( a toast).
2. attrib. use of sense 1.
3. [mid-19C+] anything unusually large or plentiful.
4. [1940s+] (W.I.) a drunkard, a habitual drinker, esp. of rum.