A reserved or overly formal manner — behaving politely but distantly, especially toward someone who is normally a friend.
久しぶりに会った友達が他人行儀で、会話がぎこちなかった。
A friend I hadn't seen in a while was very reserved, and the conversation felt awkward.
彼は職場ではいつも他人行儀だが、仲の良い人の前では別人になる。
He's always formal at work, but becomes a different person around close friends.
初対面の印象が他人行儀に感じられる場合もあるが、時間が経てば打ち解けることが多い。
Sometimes a first impression may seem distant or formal, but often people warm up over time.