A companion or the company one keeps; a person who accompanies someone.
今日は連れがいるので一人で行かなくて済む。
I have company today, so I don't have to go alone.
彼は恋人を連れ立ってパーティーに来た。
He came to the party accompanied by his partner.
犬を連れた散歩者をよく見かける公園だ。
It's a park where you often see people walking with their dogs.
In Noh theater, the secondary supporting role (tritagonist) that accompanies the main role; usually written ツレ.
能では、シテに対してツレが歌や演技で応じる役割を持つ。
In Noh, the tsure responds to the shite with singing and acting.