noun, noun or participle which takes 'suru', transitive verb
Refers to projecting images or movies onto a screen. Often used in technical or formal contexts.
映画をスクリーンに映写する。
Project a movie onto the screen.
映写室からフィルムを操作する。
Operate the film from the projection room.
投影 is a broader term for projection (including abstract concepts), while 映写 specifically refers to projecting images or films onto a screen.
Compound of 映 (ei, 'reflect, project') and 写 (sha, 'copy, photograph'). The combination conveys the idea of projecting a copied image.