Added 10 October 2026 semicircle noun Categories: Describing WordsRare Words In Latin: sēmicirculus, hēmicyclium Wiktionary noun ! Definition from WordNet 3.1, Princeton University. More about semicircle at Wordnik → Where our words come from → A plane figure with the shape of half a circle. Related Words: hemicyclearcsemiellipsesemicellsemidisksemicylindersemidomesemihemispheresemicolumnhemisegmentsemilenssemiordinate Back to today's word