If the word "Brother" is ambiguous as far as The Bible is concerned, can we be named Brothers of Jesus Christ?

According to Catholicism and some evangelical denomination in order to give justifications the perpetual virginity of Mary, they affirm that the word "Brother" in the Bible is ambiguous and include cousin and relatives. But if that is the case, _can we really be named brothers of Jesus?_ or we should be just cousins or relatives of Christ?