[hard.en] vb hard.ened ; hard.en.ing vt (13c) 1: to make hard or harder
2: to confirm in disposition, feelings, or action; esp: to make callous "~ed his heart" 3 a: inure, toughen "~ troops" b: to inure to unfavorable environmental conditions (as cold)--often used with off "~ off plants"
4: to protect from blast, heat, or radiation (as by a thick barrier or placement underground) ~ vi 1: to become hard or harder
2. a: to become firm, stable, or settled b: to assume an appearance of harshness or severity "her face ~ed at the word"