The term 'desert monster' can be summarized by the crossword solution GILA, which is a four-letter word. GILA refers to the GILA monster, a species of venomous lizard native to the deserts of the southwestern United States and northwestern Mexico. It is the only venomous lizard native to the United States and is one of the five species of venomous lizards in the world. The GILA monster is a large, heavy-bodied lizard with a wide head and short legs. It has a distinctive pattern of black, pink, and yellow scales on its back.