Is it ensure, insure, or assure?
late 14c., "to roast or dry" (peas, beans, corn, etc.), of uncertain origin. Klein and OED reject derivations from Old North French perchier (Old French percer) "to pierce" and Latin persiccare "to dry thoroughly." Barnhart suggests possibly from Middle English perchen, variant of perishen "to perish" (see perish). Klein "tentatively" suggests a back-formation from parchment. Surname Parchecorn is attested from mid-14c. Meaning "to dry with excessive heat" is mid-15c. Related: Parched; parching.