Is it ensure, insure, or assure?
1845 in biological sense, from German metabolisch (1839), from Greek metabolikos "changeable," from metabole "a change, changing, a transition" (see metabolism). Used earlier in a general sense of "involving change" (1743). Related: Metabolically.
metabolic met·a·bol·ic (mět'ə-bŏl'ĭk)
Of, relating to, or resulting from metabolism.