"that old git"
- referring to Filch (PS8)
"an ignorant old git who lived like a pig" (DH22)
"Little git," whispered Ron. "He's enjoying keeping us hanging (DH24)."
A variant of the slang noun "get," which also means an idiot (usually in Ireland or the north of England) and which was derived from a rather archaic term for the offspring of any animal (that, in turn, was derived from the verb to beget, meaning "to give birth to".