A female relative of one's parents (an aunt). 伯母 often refers to a parent's older sister, 叔母 to a younger sister; in everyday speech both are commonly called おばさん.
夏休みに伯母さんの家に遊びに行った。
I went to visit my aunt's house during summer vacation.
母の妹は叔母さんにあたる。
My mother's younger sister is my aunt (叔母).
おばさんが作ってくれた料理がおいしかった。
The food my aunt made was delicious.