Definition of soap:
(n) :
a substance able to mix with both oil and water, used for cleaning, often in the form of a solid bar or in liquid form, derived from
fats or made
synthetically; (colloquial) A
soap opera
"I tried washing my hands with soap, but the stain wouldn't go away."
(v) :
to apply soap to in washing; to cover with soap as a prank
"be sure to soap yourself well before rinsing."