He 'tempered' his criticism 'with' a few words of encouragement. = He 'tempered' his criticism 'by' adding a few words of encouragement.
He was upset but 'kept his temper'. [=remained calm; did not become angry, begin shouting, etc.]
Higher interest rates have 'tempered' [='lessened'] the demand for new houses.
(..) And I certainly don't need someone telling on me to my mother! Wait,where are you going? To my room-- and no one's allowed in! oh,he gets his temper from his daddy. - He's got my eyes. - I see. All that science stuff,that comes from jesus. Sheldon,your mom made dinner. (..)2007 TvShow: The Big Bang Theory Title: The Luminous Fish Effect Season: 1 Episode 4