1 [countable usually singular] written
the front part of a woman's chest:
She cradled the child to her bosom.
2 [countable usually plural]
a woman's breast
the situation where you feel safe because you are with people who love and protect you
4 [singular] literary
a word meaning someone's feelings and emotions, used especially when these are bad or unpleasant:
Drury harboured bitterness in his bosom.
a very close friend