lamprey (n.)Related entries & more
c. 1300 (perhaps c. 1200 as a surname), from Old French lamproie "lamprey" (12c.), from Medieval Latin lampreda, from Late Latin lampetra "lamprey," a word of uncertain origin, usually explained as literally "lick-rock," from Latin lambere "to lick" (see lap (v.1)) + petra "rock" (see petrous), but this might be folk etymology. The animals attach themselves with sucker-like mouths.
limpet (n.)Related entries & more
type of marine gastropod mollusk, early 14c., earlier lempet (early 14c.), alteration of Old English lempedu, which apparently originally meant "a lamprey" (both cling by sucking), from Medieval Latin lampreda "lamprey; limpet," from Late Latin lampetra "lamprey" (see lamprey). Limpin was a 16c. variant that survived in dialects.