1A general term for a female; depending on context it can mean 'girl' or 'woman.' Also very commonly used as a category label, e.g. in sports (女子選手 'female athlete') or social contexts (女子会 'girls' gathering').
大会には多くの女子選手が参加した。
Many female athletes participated in the tournament.
駅の案内表示に「女子トイレ」と書いてある。
The station sign says "women's restroom."
女子学生の割合が年々増えている。
The proportion of female students has been increasing year by year.
今週末、久しぶりに女子会をすることになった。
This weekend we're finally having a girls' get-together after a long time.