noun
one-act play
Refers to a play consisting of a single act, as opposed to multi-act plays.
彼の新作は一幕物だ。
His new work is a one-act play.
一幕物の上演時間は短い。
The performance time of a one-act play is short.
Compound of 一幕 (ひとまく, 'one act') and 物 (もの, 'thing, piece'), literally 'one-act piece'.