male: of the male sex, whether named as the category set beside female or as a particular male individual
This is Greek's plain word for the male sex. It says nothing about age, standing, or role, unlike the ordinary word for a grown man or a husband (ἀνήρ). It simply sorts a living thing into one of the two sexes, which is why the New Testament can use it of a newborn as readily as of an adult, and why its natural partner is the matching word for female (θῆλυς).
Most of its New Testament appearances trace back to a single Old Testament sentence. Answering a question about divorce, Jesus quotes the creation account: God made them "male and female" (Matthew 19:4, Mark 10:6). Paul reaches for the same two words in Galatians 3:28, and one small signal gives the quotation away. His first two pairs are joined by "nor" (Jew nor Greek, slave nor free), but the third is joined by "and," exactly as the Greek Old Testament joins them in Genesis. He is quoting, not merely continuing a list.
The remaining uses point at an actual male. Luke cites the law that every firstborn male belongs to the Lord (Luke 2:23). Revelation twice calls the woman's child a male (Revelation 12:5, 12:13), and the second time the Greek says only "the male," leaving "child" to be supplied from the story. In Romans 1:27 Paul writes of "males" where he could have written "men," holding the reader's attention on sex rather than on adulthood or status.
The word also supplies half of the term Paul coins for a man who takes another male sexually (ἀρσενοκοίτης), which welds this word to the word for a bed.