Hydrant and Petcock

Hydrant noun - A faucet for drawing water from a pipe or cask.

Petcock and hydrant are semantically related In some cases you can use "Petcock" instead a noun "Hydrant".

Petcock noun - Regulator consisting of a small cock or faucet or valve for letting out air or releasing compression or draining.

Hydrant and petcock are semantically related in faucet topic. You can use "Hydrant" instead a noun "Petcock".