the.com/ligand

means A ligand is an ion or molecule that binds to a central atom or receptor, often triggering a chemical or biological response.

from From Latin 'ligandum,' the gerundive of 'ligare' — 'to bind' or 'to tie' (the same root that gives us 'ligament' and 'ligature'). Chemists borrowed the term in the early 20th century for atoms or molecules clustering around a central metal ion in a coordination complex, literally the stuff 'to be bound' to it. Biology later adopted the word for molecules that latch onto receptors, keeping faithful to the original sense of binding fast.