From 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.
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2. Any person especially cherished and indulged; a fondling;
a darling; often, a favorite child; as, a teacher's pet.
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The love of cronies, pets, and favorites. --Tatler.
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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.
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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]
From 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.
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Some young lady's pet curate. --F. Harrison.
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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.]
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From 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.
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From The Collaborative International Dictionary of English v.0.48:
Pet \Pet\, v. i.
To be a pet. --Feltham.
[1913 Webster]