Refers to the role or contribution someone or something plays in a particular situation. Often used with verbs like 買う (to take on a role) or 果たす (to fulfill a role).
He took on an important role in the project.
This invention is playing a part in technological progress.
two people sharing one role
Standard kanji spelling.
Mixed kana-kanji spelling sometimes seen.
Compound of 一 (one) and 役 (role, duty).