Origin unknown. (Irish naigín, Scottish Gaelic noigean are both from English.) Compare nog.
noggin (plural noggins)
- A small mug, cup or ladle.
- (dated) A measure equivalent to a gill. Also possibly linked to the phrase “naggin of vodka” (a small bottle of vodka).
- 1836, Charles Dickens, The Pickwick Papers
- I don’t know whether…you…ever…went out to a slight lunch of a bushel of oysters, a dozen or so of bottled ale, and a noggin or two of whiskey to close up with.
- (slang) The head.
- 2003, James D. Doss, Dead Soul 
- Or maybe he bumped his noggin when he fell down—after he got clipped on the legs.
- 2003, John Farris, The Fury and the Power 
- She bumped her noggin on the bulkhead above the doorway, smiled in apology for her presumed clumsiness.
measure equivalent to a gill