水みず分ぶん子しMeanings1nounwater moleculeScientific term for a single molecule of water (H₂O). Used in chemistry and related fields.水みず分ぶん子しは酸さん素そ原げん子し一ひとつと水すい素そ原げん子し二ふたつからできている。A water molecule is made of one oxygen atom and two hydrogen atoms.