noun

• (by extension) Something kept as a companion, including inanimate objects (pet rock, pet plant, etc.).
  "Papyrus: This is my brother's pet rock. He always forgets to feed it. As usual, I have to take responsibility."

verb

• (transitive) To stroke or fondle (an animal).
  "I really love to pet cute puppies."
• (transitive, intransitive, informal) To stroke or fondle (another person) amorously.
  "We started petting each other the moment we were alone."
• (dated, transitive) To treat as a pet; to fondle; to indulge.
  "His daughter was petted and spoiled."
• (archaic, intransitive) To be a pet.

adj

• (figurative) Favourite; cherished; the focus of one's (usually positive) attention.
  "a pet project"
• (literally) Kept or treated as a pet.
  "pet rock"
• (obsolete) Good; ideal.
  "“Now,” said Hands, “look there; there’s a pet bit for to beach a ship in. Fine flat sand, never a cat's paw, trees all around of it, and flowers a-blowing like a garding on that old ship.”"

noun

• (Ireland, Geordie) A term of endearment usually applied to women and children.