What prefix is associated with the word 'sinus'?

The prefix associated with the word 'sinus' is indeed 'sin/o.' In medical terminology, 'sinus' refers to a cavity or a space within a bone, often associated with the respiratory tract, such as the paranasal sinuses. The prefix 'sin/o' is specifically used to denote anything related to sinuses in various medical contexts.

The use of 'sin/o' helps to form terms that pertain to conditions, diseases, or anatomical descriptions involving the sinuses. For example, 'sinusitis' refers to the inflammation of the sinuses. This prefix is essential in clearly identifying the anatomical structures and associated conditions in medical language.

Other prefixes listed relate to different anatomical areas. For instance, 'rhin/o' refers to the nose, while 'naso' also pertains to the nose but is less commonly used as a prefix directly associated with sinus terminology. 'Sphenoid/o' is used to describe the sphenoid bone, not directly related to the sinus definitions. Therefore, 'sin/o' is the correct choice as it is specifically linked to the term 'sinus.'