phrases whose literal meaning...

[James A. Landau]

My daughter needs to know the term to be applied to phrases whose literal
meaning is one thing but which are universally interpreted as something else.
 Her examples are "How do you do?" which literally asks "How are you?" but is
used merely as "Hello"; and one from Hebrew, "mazel tov" which literally
means "good luck" but is universally used as "congratulations".

     - Jim Landau