What is Man?

Legal Definition
A man is a male human. The term man is usually reserved for an adult male, with the term boy being the usual term for a male child or adolescent. However, the term man is also sometimes used to identify a male human, regardless of age, as in phrases such as "men's basketball".

Like most other male mammals, a man's genome typically inherits an X chromosome from his mother and a Y chromosome from his father. The male fetus produces larger amounts of androgens and smaller amounts of estrogens than a female fetus. This difference in the relative amounts of these sex steroids is largely responsible for the physiological differences that distinguish men from women. During puberty, hormones which stimulate androgen production result in the development of secondary sexual characteristics, thus exhibiting greater differences between the sexes. However, there are exceptions to the above for some intersex and transgender men.
-- Wikipedia
Legal Definition
A human being. This definition includes not only the adult male sex of the human species, but women and children; examples: "of offences against man, some are more immediately against the king, other's more immediately against the subject." Hawk. P. C. book 1, c. 2, s. 1. Offences against the life of man come under the general name of homicide, which in our law signifies the killing of a man by a man." Id. book 1, c. 8, s. 2.

2. In a more confined sense, man means a person of the male sex; and sometimes it signifies a male of the human species above the age of puberty. Vide Rape. It was considered in the civil or Roman law, that although man and person are synonymous in grammar, they had a different acceptation in law; all persons were men, but all men, for example, slaves, were not persons, but things. Vide Barr. on the Stat. 216, note.
-- Bouviers Law Dictionary
Legal Definition
A human being. A person of the male sex. A male of the human species above the age of puberty. In feudal law. A vassal; a tenant or feudatory. The Anglo-Saxon relation of lord and man was originally purely personal, and founded on mutual contract. 1 Spence, Ch. 37. See Man of straw.
-- Black's Law Dictionary