Merriam-Webster's Collegiate® Dictionary, 11th Edition
SHARK
I. noun
Etymology: Middle English
Date: 15th century
any of numerous mostly marine cartilaginous fishes of medium to large size that have a fusiform body, lateral branchial clefts, and a tough usually dull gray skin roughened by minute tubercles and are typically active predators sometimes dangerous to humans, sharklike adjective
II. noun
Etymology: probably modification of German Schurke scoundrel
Date: 1599
a rapacious crafty person who takes advantage of others often through usury, extortion, or devious means , one who excels greatly especially in a particular field,
III. verb
Date: 1602
transitive verb to gather hastily, to obtain by some irregular means, intransitive verb to practice fraud or trickery, sneak