insulin

Insulin takes its name from Latin īnsula, meaning 'island,' plus the chemical suffix -in. It's named for the islets of Langerhans, the small clusters of cells in the pancreas where it's produced.

The word was coined directly to describe the hormone's source rather than shifting from an earlier meaning — it points straight at the 'islets' where these cells sit apart from surrounding tissue.

It shares its root with 'isle' and 'insular,' both of which trace back to the same Latin īnsula.