Is it ensure, insure, or assure?
1580s, "want of civilized behavior, rudeness," from French incivilité (early 15c.), from Late Latin incivilitatem (nominative incivilitas), from incivilis "not civil," from in- "not, opposite of" (see in- (1)) + civilis "relating to a citizen, relating to public life, befitting a citizen; popular, affable, courteous" (see civil). Meaning "an act of rudeness" is from 1650s. Incivil "not conducive to common good" is from mid-15c.