In English, lower case man (pl. men) refers to an adult human male (the term boy is the usual term for a human male child or adolescent). Sometimes it is also used as an adjective to identify a set of male humans, regardless of age, as in phrases such as "men's rights". Although men typically have a male reproductive system, some intersex people with ambiguous genitals, and biologically female transgender people, may also be classified or self-identify as a "man".

The term manhood is used to refer to masculinity, the various qualities and characteristics attributed to men such as strength and male sexuality.

The English term "man" is derived from Old English mann. The Old English form had a default meaning of "adult male" (which was the exclusive meaning of "wer"), though it could signify a person of unspecified gender. The closely related "man" was used just as it is in Modern German to designate "one" (e.g., as in the saying Man muss mit den Wölfen heulen). The Old English form is derived from Proto-Germanic *mannaz, "persona", which is also the etonym of German Mann "man, husband" and man "one" (pronoun), Old Norse maðr, and Gothic manna. According to Tacitus, the mythological progenitor of the Germanic tribes was called Mannus. The Germanic form is in turn derived from the Proto-Indo-European root *manu-s "man, person", which is also the root of the Indian name Manu, mythological progenitor of the Hindus.