permastoneEtymologyA genericization from a trade name of the 1940s, Perma-Stone, itself a proprialization from what had previously been a lexical gap affixation, perma- + stone.permastone means any superficial surface constructed to look like stonework, usually made of concrete or thin sheets of rock assembled over an existing surface. Lexicurio rates it Sui generis — a strength score of 88 out of 100.nounAny superficial surface constructed to look like stonework, usually made of concrete or thin sheets of rock assembled over an existing surface.“Near-synonym: formstone (broadly synonymous)”