|män, |mōn+ adjective
Etymology: mon- + atomic
1.
a. : consisting of one atom : having one atom in the molecule : atomic 5
helium is a monatomic gas
monatomic metals
b. : having a thickness equal to the diameter of a constituent atom
a monatomic layer of cesium
2. : univalent
3. : having one replaceable atom or radical
monatomic alcohols