Excipient
Any ingredient in a supplement other than the active compounds -- fillers, binders, coatings, colors, and sweeteners. Excipients are declared in a label's "other ingredients" section, separate from the Supplement Facts panel's active ingredients.
Example
Titanium dioxide, an excipient used to whiten tablet and capsule coatings, appears on 4,518 on-market products despite being removed from the EU's authorized food additives in 2022.