Which combining form is used to describe old age in medical terms?

• A. Noct/i
• B. Proxim/o
• C. Dent/i
• D. Geront/o

Answer: (D)

Old age is conveyed by the combining form geront/o. This root appears in terms like gerontology (the study of aging), geriatric (pertaining to elderly people), and gerontologist (a specialist in aging). That direct link to aging is what makes it the best choice. The other roots point to completely different ideas: noct- relates to night, proxim- means near, and dent- refers to tooth, so they don’t describe aging. The combining vowel o is used to connect the root to suffixes, helping form words like geront/o logy or geront/o ist.