The term 'Ancient Italian Deity' can be summarized by the crossword solution 'FAUN', which is a four-letter word. Fauns are mythological creatures in Roman mythology, often depicted as half-man and half-goat. They were associated with nature, fertility, and music, and were thought to inhabit rural areas and forests. Fauns were also believed to be guardians of the Roman gods, and were often seen as benevolent spirits.