a (tennis) Describing the sets in a match of which the winner did not lose a single set. (defdate|from 19th c.)
a (cricket) Describing the bat as held so as not to incline to either side; on, or near a line running between the two wickets. (defdate|from 19th c.)
a (colloquial) conventional | Conventional, socially acceptable; unadventurous. (defdate|from 20th c.)
a (colloquial|slang|pejorative) (non-gloss definition|Used to express dislike): boredom | Boring, unimaginative, inferior. (defdate|from 20th c.)
n (slang) A cigarette, particularly one containing tobacco instead of marijuana. Also straighter |straighter. (defdate|from 20th c.)