Thinking about the bifurcated pronunciation of “retard”. Like, “with the brakes applied, downhill acceleration is retarded” would be pronounced pretty much like a diagnostic “the nuns worked with deaf-mutes and retarded children” or colloquial “episodes 7-9 were retreads, but the prequels were retarded”
But where “the membrane will retard saltwater infiltration of the aquifer” would be like a clipped British “ritard”, it’d be “John is a REE-tard”