E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Wit to turn things to account, capacity. In Yorkshire we hear the phrase, I canna gaum it (understand it, make it out), and gaumtion is the capacity of understanding, etc. (Irish, gomsh, sense, cuteness.)
Though his eyes were dazzled with the splendour of the place, faith he had gomsh enough not to let go his hold.Dublin and London Magazine, 1825 (Loughleagh).
Gumption. A nostrum much in request by painters in search of the supposed lost medium of the old masters, and to which their unapproachable excellence is ascribed. The medium is made of gum mastic and linseed-oil.