ˈtəfən verb
( toughened ; toughened ; toughening -f(ə)niŋ ; toughens )
Etymology: tough (I) + -en
transitive verb
: to make tough
toughened by a rough-and-tumble environment where each man's revolver … made the law — R.A.Billington
intransitive verb
: to become tough
the language has suddenly toughened and acquired a new menacing cadence — Edmund Stevens