One who laps liquid, who takes liquid in with the tongue.
1913, William Atherton Du Puy , Uncle Sam, Wonder Worker Chapter , ...that recipient of the favors and caresses of the hearthstone, that lapper of milk from the national saucer, the cat.
1827, ?, Blackwood's Edinburgh Magazine Chapter , The pupils of the modern school discover in lion but the crafty, cruel, and cowardly lapper of blood.
(in combination) something (especially a race) that is a stated number of laps e.g. a 25-lapper
2001, Tim Bongard, Richard Petty: The Cars of the King Chapter , ...Richard Petty Private Collection outran Buck Baker's '62 Chrysler to win the 200-lapper. One week later, Jim Paschal finished second to race winner Junior.
(sports) A competitor who is one lap behind another, in the same race, and hence physically in front.
To make a gentle splashing sound, as the sound of flowing water.
1900?, S.R. Crockett, The Red Axe Chapter XXXVII, There was mockery of our foolhardy enterprise in the soft whispering sough of the water, as I heard it lapper beneath the ferry-boat that lay ready to cross to the other side.