English gain-

← Old English geġn- (inherited)

← Old English gēan- (mention)

← German gegen- (cognate)

← English again (link)

← Middle English gain- (inherited)

← Proto-Germanic *gagin (inherited)

← Icelandic gagn- (cognate)

← Dutch tegen- (cognate)

→ English gain (link)

→ English re- (link)

→ German gegen- (cognate)

→ Irish go (cognate)

→ Alemannic German go (mention)

→ Old Irish co (cognate)