Coplin rhymes with:
koplin, kopplin, choplin, joplin, koplin, kopplin, poplin, aplin, applin, caplin, champlin, choplin, eplin, esplin, joplin, kaplin, kemplin, koplin, kopplin, pamplin, poplin, striplin, tamplin, taplin, templin
Coplin sounds like:
cableone, caplan, caplin, cephalon, chaplain, chaplan, chaplin, choplin, cipollone, civilian, cofflin, copelan, copelin, coplan, coplen, coppolino, couvillion, couvillon