四环素 sìhuánsù tetracycline Origin Definitions Defs Strokes Stroke Words Sentences Sents 四 sì numeral four the number four; complex form used for financial purposes is 肆 sì环 環 huán noun ring (bound form) any ring-shaped object; a hoop, loop, or chain link素 sù noun element (bound form) essential part; element; constituent; basic nature