Is it ensure, insure, or assure?
also ischemia, 1866 (but as far back as 1660s in form ischaimes), from medical Latin ischaemia, from ischaemus "stopping blood," from Greek iskhaimos "stanching or stopping of blood," from iskhein "to hold" + haima "blood" (see -emia). Related: Ischemic.
ischemia is·che·mi·a (ĭ-skē'mē-ə)
A decrease in the blood supply to a bodily organ, tissue, or part caused by constriction or obstruction of the blood vessels.