n.
 the mass or line of foam formed by waves breaking on a seashore or reef.
v.
  - stand or lie on a surfboard and ride on the crest of a wave towards the shore. 
▸informal ride on the roof or outside of a fast-moving vehicle, typically a train, for excitement.
 - move from site to site on (the Internet).
 
 
  Derivative
  
    - surfer n.
  - surfing n.
  - surfy adj.
 
   
  Etymology
  C17: appar. from obs. suff, of unknown origin, perh. influenced by the spelling of surge.