The Collaborative International Dictionary of English v.0.48:

pet \pet\ (p[e^]t), n. [Formerly peat, perhaps from Ir. peat,
   akin to Gael. peata.]
   1. A cade lamb; a lamb brought up by hand.
      [1913 Webster]

   2. Any person especially cherished and indulged; a fondling;
      a darling; often, a favorite child; as, a teacher's pet.
      [1913 Webster + PJC]

            The love of cronies, pets, and favorites. --Tatler.
      [1913 Webster]

   3. [Prob. fr. Pet a fondling, hence, the behavior or humor
      of a spoiled child.] A slight fit of peevishness or
      fretfulness. "In a pet she started up." --Tennyson.
      [1913 Webster]

   4. Any animal kept as a companion, usually in or around one's
      home, typically domesticated and cared for attentively and
      often affectionately. Distinguished from animals raised
      for food or to perform useful tasks, as a draft animal
      or a farm animal.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

pet \pet\, a.
   Petted; indulged; favorite; admired; cherished; as, a pet
   child; a pet lamb; a pet theory; a pet animal.
   [1913 Webster]

         Some young lady's pet curate.            --F. Harrison.
   [1913 Webster]

   Pet cock. [Perh. for petty cock.] (Mach.) A little faucet
      in a water pipe or pump, to let air out, or at the end of
      a steam cylinder, to drain it. [Also spelled petcock.]
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pet \Pet\, v. t. [imp. & p. p. Petted; p. pr. & vb. n.
   Petting.]
   To treat as a pet; to fondle; to indulge; as, she was petted
   and spoiled.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Pet \Pet\, v. i.
   To be a pet. --Feltham.
   [1913 Webster]

WordNet (r) 3.0 (2006):

pet
    adj 1: preferred above all others and treated with partiality;
           "the favored child" [syn: favored, favorite(a),
           favourite(a), best-loved, pet, preferred,
           preferent]
    n 1: a domesticated animal kept for companionship or amusement
    2: a special loved one [syn: darling, favorite, favourite,
       pet, dearie, deary, ducky]
    3: a fit of petulance or sulkiness (especially at what is felt
       to be a slight)
    4: using a computerized radiographic technique to examine the
       metabolic activity in various tissues (especially in the
       brain) [syn: positron emission tomography, PET]
    v 1: stroke or caress gently; "pet the lamb"
    2: stroke or caress in an erotic manner, as during lovemaking

Moby Thesaurus II by Grady Ward, 1.0:

102 Moby Thesaurus words for "pet":
   admired, adored, angel, babe, baby, baby-doll, beloved,
   bill and coo, buttercup, caress, cherished, cherub, chick,
   chickabiddy, cocker, coddle, copulate, cosset, cuddle, dally,
   dandle, darling, dear, dearly beloved, deary, doll, duck, duckling,
   dudgeon, embrace, esteemed, favorite, feel up, ferment, fondle,
   fondling, fret, frictionize, fume, grump, held dear, high dudgeon,
   hon, honey, honey bunch, honey child, huff, hug, idol, jewel,
   knead, lamb, lambkin, lollygag, love, loved, lover, make love,
   make out, massage, matinee idol, miff, minion, neck, nose, nuzzle,
   pat, petkins, pique, popular, pout, precious, precious heart,
   preference, prized, revered, rub, rub against, rub down, rub noses,
   smooch, snookums, spoiled child, spoon, stew, stroke, sugar, sweet,
   sweet-talk, sweetheart, sweetie, sweetkins, sweets, tiff, toy,
   treasured, trifle, wanton, well-beloved, well-liked,
   whisper sweet nothings, white-haired



V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

PET
       Personal Electronic Translator


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

PET
       Privacy Enhancement Technology


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

PET
       Print Enhancement Technology (Compaq)


V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

PET
       Progressive Educational Technology