inure (v.)

formerly also enure, mid-15c., "accustom, adapt, establish by use," contracted from phrase (put) in ure "in practice" (early 15c.), from obsolete noun ure "work, practice, exercise, use," probably from Old French uevre, oeuvre "work," from Latin opera "work" (from PIE root *op- "to work, produce in abundance"). Meaning "toughen or harden by experience" is from late 15c. Related: Inured; inuring.