The word "deltoidal" is a specific term used to refer to a shape that is similar to a delta or triangular in nature. However, there are a few synonyms that can be used instead of deltoidal to describe a triangular or delta-shaped object. These synonyms include triangular, trilateral, pyramidal, and triangular-shaped. These words can be used interchangeably with deltoidal to express the same idea of describing an object with three sides that is shaped like a delta or triangle. Using these synonyms can help to add variety and depth to your writing while still expressing the same meaning as deltoidal.