Is it ensure, insure, or assure?
1610s, from Middle French recurrent (16c.) and directly from Latin recurrentem (nominative recurrens), present participle of recurrere "run back, hasten back, return" (see recur). From 1590s as a noun ("recurrent muscle").
recurrent re·cur·rent (rĭ-kûr'ənt, -kŭr'-)
Occurring or appearing again or repeatedly.
Turning in a reverse direction. Used of blood vessels and nerves.