Words at Play : Top 10 Favorite British Words, Vol. 1
Definition:
lacking intelligence: stupid
Example:
"Gormless, unhelpful and poorly trained shop staff create merry hell for customers who are simply exercising their legal rights to a repair, refund or replacement." Sam Dunn, Two Pennies Worth blog, March 22, 2011
About the word:
The word gaum exists in some English dialects and means "attention or understanding." Someone without gaum (or gorm) lacks understanding.