SEMICIRCLE Meaning of SEMICIRCLE in English [semi.cir.cle] n [L semicirculus, fr. semi- + circulus circle] (1526) 1: a half of a circle 2: an object or arrangement of objects in the form of a half circle -- semi.cir.cu.lar adj Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012