late 13c., "gum or other substance producing a sweet smell when burned," from Old French encens (12c.), from Late Latin incensum "burnt incense," literally "that which is burnt," noun use of neuter past participle of Latin incendere "set on fire" (see incendiary). Meaning "smoke or perfume of incense" is from late 14c.
early 15c., encensen "to arouse, inspire," from Old French incenser, from Latin incensare, frequentative of incendere "set on fire," figuratively "incite, enrage, rouse" (see incendiary). From mid-15c. as "to provoke, anger." Literal sense "to heat, make (something) hot" is from c. 1500 in English but is rare.
"to offer incense, perfume with incense, fumigate (something) with incense," late 13c., encensen, incensen, from incense (n.) or from Old French encenser (11c.), or directly from Medieval Latin incensare.