"Fistular" is a relatively uncommon word, more commonly spelled as "fistulous," which refers to the formation of a fistula or an abnormal connection between two cavities in the body that are not normally connected. Synonyms for fistular include fistulose, sinusoidal, and tubular. Other related terms may include perforation, opening, and hollow. While these words may not be direct synonyms, they share similar meanings to fistular and are often used in medical or anatomical contexts to describe abnormalities or connections within the body. It is important to use precise language in discussions about health and medicine, and having a robust vocabulary of related terms can be helpful.