'petcock' definitions:

Definition of 'petcock'

(from WordNet)
noun
Regulator consisting of a small cock or faucet or valve for letting out air or releasing compression or draining

Definition of 'petcock'

From: GCIDE
  • 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]

Definition of 'petcock'

From: GCIDE
  • petcock \pet"cock`\ (p[e^]t"k[o^]k`) n. A small cock or faucet or valve for letting out air or releasing compression, or for draining a vessel. [WordNet 1.5]