Slap (?), n. [OE. slappe; akin to LG. slappe, G. schlappe; probably of imitative origin.]
A blow, esp. one given with the open hand, or with something broad.
© Webster 1913.
Slap, v. t. [imp. & p. p. Slapped (?); p. pr. & vb. n. Slapping.]
To strike with the open hand, or with something broad.
© Webster 1913.
Slap, adv. [Cf. LG. slap, G. schlapp. See Slap, n.]
With a sudden and violent blow; hence, quickly; instantly; directly.
[Colloq.] "The railroad cars drive
slap into the city."
Thackeray.
© Webster 1913.