Is it ensure, insure, or assure?
1750, coined from anti- "against" + septic. Figurative use by 1820. As a noun meaning "an antiseptic substance" by 1803.
antiseptic an·ti·sep·tic (ān'tĭ-sěp'tĭk)adj.
Of, relating to, or producing antisepsis.
Capable of preventing infection by inhibiting the growth of infectious agents.