join·er 
/ˈʤoɪnɚ/ noun
plural join·ers /ˈʤoɪnɚ/ noun [count] 1 US : a person who joins many organizations
▪ He's not a joiner. He prefers to do things by himself. 2 chiefly Brit : a person whose job is to build things (such as door or window frames) by joining pieces of wood
▪ He's not a joiner. He prefers to do things by himself.
