[alteration of undercumstand < understand]
UK dialect : to understand (also undercumstumble)
"Waiting, guvnor? Most deciduously. Bet your boots on.
Stunned like, seeing as how no shiners is acoming.
Underconstumble?"
- James Joyce, Ulysses (1922)
"I undercumstumble our little Francesca -- we shall see her
trotting home one of these days, you mark my words."
- E. M. Delafield, The Pelicans (1919)
-tsuwm
http://home.comcast.net/~wwftd