Is it ensure, insure, or assure?
late 14c., from Latin mendicantem (nominative mendicans) present participle of mendicare "to beg, ask alms," from mendicus "beggar," originally "cripple" (connection via cripples who must beg), from menda "fault, physical defect" (see mendacious). As an adjective from 1540s. Also in Middle English was mendinant (mid-14c.), from Old French mendinant, present participle of mendiner "to beg," from the same Latin source.
"a beggar," mid-15c., from mendicant (adj.) or from Latin mendicantem (nominative mendicans), noun use of present participle of mendicare.