Meaning

noun (physics and chemistry) the simplest structural unit of an element or compound

noun (nontechnical usage) a tiny piece of anything

originEtymology tree Latin mōlēs Proto-Indo-European *-lós Proto-Indo-European *-elós Proto-Italic *-elos Proto-Italic *-kelos New Latin -cula New Latin moleculalbor. French moléculebor. English molecule Borrowed from French molécule, from New Latin molecula (“a molecule”), diminutive of Latin moles (“a mass”).

Etymology from Wiktionary, CC BY-SA 3.0