(often foll by against) to guarantee or protect (against risk, loss, etc): we insured against disappointment by making an early reservation
(often foll by against) to issue (a person) with an insurance policy or take out an insurance policy (on): his house was heavily insured against fire, after all his car accidents the company refuses to insure him again
another word (esp US) for ensure (sense 1), ensure (sense 2)
mid-15c., insuren, spelling variant of ensuren (see ensure). Took on its particular sense of "make safe against loss by payment of premiums" from mid-17c. (replacing assure in that meaning). Related: Insured; insuring.