noun
leaving the nest; fledging
Literal use for a young bird leaving its nest. Often appears with birds such as ツバメ or ひな.
ツバメの巣立ちを家族で見守った。
Our family watched the swallows leave the nest.
Graduation day is the day the students go out into the world.
親として、子どもの巣立ちはうれしくもあり寂しくもある。
As a parent, a child's becoming independent is both happy and lonely.
Focuses on being able to stand on one's own or support oneself; 巣立ち focuses on the departure or transition into independence.
A noun form related to 巣立つ, from 巣 meaning 'nest' and 立つ/立ち in the sense of setting out or rising from a place. The spelling directly reflects the literal image of leaving the nest.