excipient

/ɪkˈsɪpiənt/
noun
  1. An inactive substance that serves as a carrier or medium for a drug or other active ingredient in a medicine.
    • The pill contains the active drug plus excipients like lactose and starch.
    • Some people are allergic to certain excipients found in medications.
    • The excipient helps the medicine hold its shape and be easier to swallow.