/rum"dum'/ , Slang.
n.
1. a stupid or ignorant person.
2. drunkard; lush.
adj.
3. stupid; ignorant.
4. of, pertaining to, characteristic of, or arising from habitual drunkenness; addled by drink.
Also, rum-dumb, rum-dumm .
[ 1890-95; rhyming compound with RUM 1 and DUMB, perh. influenced in sense by HUMDRUM ]