pleurothetismEtymologyBy surface analysis, pleuro- + -thet(ic) + -ism. (Second element from Ancient Greek τίθημι (títhēmi, “I place”).)pleurothetism means A pattern of orientation among most bivalves whereby they come to rest on their left or right sides. Lexicurio rates it Rare gem — a strength score of 83 out of 100.nounA pattern of orientation among most bivalves whereby they come to rest on their left or right sides.