noun
surtitle; supertitle
Technical term used in theater, opera, or film for translated or explanatory text projected above the stage or screen.
オペラの上演では、上部字幕が観客の理解を助ける。
During opera performances, surtitles help the audience understand.
字幕 is the general term for subtitles or captions, usually at the bottom of the screen. 上部字幕 specifically refers to surtitles displayed above the stage or screen.
Compound of 上部 (じょうぶ, 'upper part') and 字幕 (じまく, 'subtitle/caption'), literally 'upper subtitle'.