四面体 sìmiàntǐ tetrahedron Origin Definitions Defs Strokes Stroke Words Sentences Sents 四 sì numeral four the number four; complex form used for financial purposes is 肆 sì面 miàn noun surface surface; top; the outside or right side of a garment or fabric体 體 tǐ noun form (bound form) the form, state, or shape of a substance, such as a solid or liquid; the configuration or structure of an object