- molecule - (physics and chemistry) the simplest structural unit of an element or compound
--1 is a kind of unit, building block
--1 has parts:
--1 has particulars:chain, chemical chain; atom; group, radical, chemical group dipole molecule; protein molecule; coenzyme; macromolecule, supermolecule - atom, molecule, particle, corpuscle, mote, speck - (nontechnical usage) a tiny piece of anything
--2 is a kind of material, stuff
--2 has particulars: grain; chylomicron; flyspeck - atom, molecule, particle, corpuscle, mote, speck - (nontechnical usage) a tiny piece of anything