noun
A dog without an owner, living on the streets or in the wild.
公園に野良犬がいた。
There was a stray dog in the park.
野良猫 means 'stray cat', while 野良犬 specifically refers to a stray dog.
Compound of 野良 (のら, 'field' or 'wild') and 犬 (いぬ, 'dog'). The exact historical derivation is uncertain, but the word has been used to refer to ownerless dogs since at least the Edo period.