fellatio /(fĕl*lā"shē*ō̇; fĕl*lā"tē*ō̇)/

fel·la·ti·o

fellatio

n.
  1. a form of sexual activity between two persons in which the penis of one is stimulated by the other's mouth, especially until orgasm is achieved. It is a form of oral sex. Compare cunnilingus. The act is also called by the slang term blow job.