Koplin rhymes with:
coplin, kopplin, choplin, coplin, joplin, kopplin, poplin, aplin, applin, caplin, champlin, choplin, coplin, eplin, esplin, joplin, kaplin, kemplin, kopplin, pamplin, poplin, striplin, tamplin, taplin, templin
Koplin sounds like:
kaplain, kaplan, kaplin, kappelman, kevlin, kopelman, koplan, koppelman, kopplin