recurring (adj.)

late 14c., recuren, "to recover from illness or suffering" (a sense now obsolete); mid-15c., "to return" (to or into a place), from Latin recurrere "to return, run back, hasten back," figuratively "revert, recur," from re- "back, again" (see re-) + currere "to run" (from PIE root *kers- "to run"). Originally of persons; application to thoughts, ideas, etc., "return to the mind," is recorded from 1620s. Meaning "happen again" is from 1670s. Related: Recurred; recurring.