excipient

ex·cip·i·ent

noun \ik-ˈsip-ē-ənt\

Definition of EXCIPIENT

: a usually inert substance (as gum arabic, syrup, lanolin, or starch) that forms a vehicle (as for a drug or antigen); especially : one that in the presence of sufficient liquid gives a medicated mixture the adhesive quality needed for the preparation of pills or tablets