Webster's 1828 Dictionary
LAMPREY
n.[L. labor, to slip, and most probably the animal is name from slipping. If, however, the sense is taken from licking the rocks, as Camden supposes, it accords with the sense of the technical name of the genus petromyzon, the rock-sucker.] A genus of anguilliform fishes, resembling the eel, and moving in water by winding, like the serpent on land. This fish has seven spiracles on each side of the neck, and a fistula or aperture on the top of the head, but no pectoral or ventral fins. The marine or sea lamprey is sometimes found so large as to weigh four or five pounds.
Lamprel and lampron. [See Lamprey. ]
Webster's 1913 Dictionary
LAMPREY
Lam "prey, n.; pl. Lampreys. Etym: [OE. lampreie, F. lamproie, LL. lampreda, lampetra, from L. lambere to lick + petra rock, stone. The lampreys are so called because they attach themselves with their circular mouths to rocks and stones, whence they are also called rocksuckers. See Lap to drink, Petrify. ] (Zoöl.)
Defn: An eel-like marsipobranch of the genus Petromyzon, and allied genera. The lampreys have a round, sucking mouth, without jaws, but set with numerous minute teeth, and one to three larger teeth on the palate (see Illust. of Cyclostomi ). There are seven small branchial openings on each side. [Written also lamper eel, lamprel, and lampron. ]
Note: The common or sea lamprey of America and Europe (Petromyzon marinus ), which in spring ascends rivers to spawn, is considered excellent food by many, and is sold as a market fish in some localities. The smaller river lampreys mostly belong to the genus Ammocoeles, or Lampetra, as A. fluviatilis, of Europe, and A. æpypterus of America. All lampreys attach themselves to other fishes, as parasites, by means of the suckerlike mouth.
New American Oxford Dictionary
lamprey
lam prey |ˈlamprē, -prā ˈlæmpri | ▶noun ( pl. lampreys ) an eellike aquatic jawless vertebrate that has a sucker mouth with horny teeth and a rasping tongue. The adult is often parasitic, attaching itself to other fish and sucking their blood. [Family Petromyzonidae: several genera and species. ] ORIGIN Middle English: from Old French lampreie, from medieval Latin lampreda, probably from Latin lambere ‘to lick ’ + petra ‘stone ’ (because the lamprey attaches itself to stones by its mouth ).
Oxford Dictionary
lamprey
lamprey |ˈlampri | ▶noun ( pl. lampreys ) an eel-like aquatic jawless vertebrate that has a sucker mouth with horny teeth and a rasping tongue. The adult is often parasitic, attaching itself to other fish and sucking their blood. ●Family Petromyzonidae: several genera and species. ORIGIN Middle English: from Old French lampreie, from medieval Latin lampreda, probably from Latin lambere ‘to lick ’ + petra ‘stone ’ (because the lamprey attaches itself to stones by its mouth ).
The Wordsmith Dictionary