The dictionary says about men:
1. An adult male person.
2. A human regardless of sex or age; a person.
3. Often used in combination (that cracks me up!).
4. A member of the genus Homo, family Hominidae, order Primates, class Mammalia, characterized by erect posture and an opposable thumb, especially a member of the only extant species, Homo sapiens, distinguished by a highly developed brain (sometimes I doubt about), the capacity for abstract reasoning (IMHO too abstract), and the ability to communicate by means of organized speech (sadly!)
5. A male lover or sweetheart (what more do we need to know?).
Here is an example of a man who knows how to use a thumb: