委员 (wěiyuán) means "committee member" or "commissioner" and is used in political and organizational contexts. It often appears as part of larger compound titles like 委员会 (wěiyuánhuì, "committee" or "commission"). For example, 证券交易委员会 is the Securities and Exchange Commission.
她是这个委员会里最年轻的委员。
Tā shì zhège wěiyuánhuì lǐ zuì niánqīng de wěiyuán.
She is the youngest member of this committee.
每位委员都对新方案发表了意见。
Měi wèi wěiyuán dōu duì xīn fāng'àn fābiǎo le yìjiàn.
Every committee member expressed their opinion on the new proposal.
他被选为教育委员会的委员。
Tā bèi xuǎn wéi jiàoyù wěiyuánhuì de wěiyuán.
He was elected as a member of the education committee.