[throw.away] n (1903) 1: one that is or is designed to be thrown away: as a: a free handbill or circular b: a line of dialogue (as in a play) de-emphasized by casual delivery; esp: a joke or witticism delivered casually
2: something made or done without care or interest
[2]throwaway adj (1928) 1: designed to be thrown away: disposable "~ containers"
2: written or spoken (as in a play) in a low-key or unemphatic manner "~ lines"
3: nonchalant, casual