expression, noun-modifying (irregular)
flat; insipid; lifeless; listless
Describes something that has lost its fizz, energy, or spirit. Often used for drinks that have gone flat, or for a person's expression, atmosphere, or performance that feels dull and lacking vitality.
See also: 気が抜ける (きがぬける)
気の抜けたコーラはまずい。
Flat cola tastes bad.
彼は気の抜けた顔で座っていた。
He sat there with a listless expression.