From Teflpedia

A woman is an adult female human.

The word woman marks the feminine gender, and forms a masculine-feminine pair with the word "man".

Woman is an irregular plural, with the plural "women" /ˈwɪmɪn/; the spelling mirrors that of man-men but the pronunciation does not.

Woman forms a number of compound nouns, e.g. Englishwoman, policewoman, etc. These are not gender neutral, so in some circumstances for some meanings gender neutral language is preferred.