Final answer:
The suffix '-ptosis' refers to sagging or prolapse in medical terms. It is used to describe the condition of falling or downward displacement of a body part, as seen in 'blepharoptosis' for sagging eyelids.
Step-by-step explanation:
The suffix that denotes sagging or prolapse in medical terminology is -ptosis. This suffix is commonly used to form nouns that describe the falling, drooping, or downward displacement of a body part. For example, in the term gastropexy, which is a surgical fixation to prevent the stomach from twisting or moving out of place, the root word 'gastro-' relates to the stomach, and the suffix '-pexy' means fixation to prevent prolapse. Similarly, 'blepharoptosis' refers to the prolapse or sagging of the eyelid.