From Old Norse félagi ('business partner'), combining fé ('cattle, money') and lag ('laying down'), fellow evolved from a commercial term to a general word for companion or peer.
A man or boy, or a person in the same position or involved in the same activity as another; also a member of a learned society or a senior member of a college.
From Old Norse félagi, meaning 'partner, one who lays down money in a joint venture,' compounded from fé ('money, cattle, property') and lag ('a laying down, something laid'). The word entered Old English as fēolaga during the Danelaw period, when Norse settlers brought their legal and commercial vocabulary to England. The original sense was strictly commercial — a fellow was someone who pooled their wealth