Female and male share a spelling but not an origin
In biology, being female comes down to one thing: producing the larger sex cell, the egg. The English word, meanwhile, has a quirky history. It descends from a Latin word for a little woman and has no real kinship with male; scribes in the late 1300s simply reshaped its spelling to rhyme with it.
Biologists define an organism as female if it makes ova, the gametes that fuse with sperm in sexual reproduction. Female gametes are larger than male ones, a system called anisogamy. In some species the two kinds of gamete are the same size, a pattern known as isogamy, where mating types differ only at the molecular level. Humans belong to the oogamous group, in which the egg is much bigger than the sperm and cannot move at all. One argument holds that this arrangement arose from the physical problem of getting two gametes together.
Beyond that defining difference, traits of females vary widely between species. Sex may be set by chromosomes, as in most mammals, where females typically carry two X chromosomes, or by environmental conditions. Some species show secondary features such as mammary glands, and some females can reproduce alone through parthenogenesis. The concept extends well beyond animals: diatoms, water moulds, chytrids and land plants all produce egg cells.
The word came into English through Old French femelle, from Latin femella, a diminutive of femina, woman. For its first century it referred only to women and girls; around a hundred years later it widened to cover other creatures. Oddly, using it as a noun was once regarded as more respectful than woman or lady, but by 1895 fashion had turned and it was often heard as belittling, since it lumped people in with animals.
Today the noun appears mostly for animals, in impersonal technical writing about human biology, or to cover people regardless of age or status. The adjective still marks sex where it matters, as in female athletes. In people, the term can also describe gender identity or role, which is conceptually distinct from biological sex. Engineers use it too: sockets and receptacles are female, the plugs that fit them male.
Source: Female
