From Longman Dictionary of Contemporary Englishhammer something ↔ in (also hammer something into somebody) phrasal verbREPEATto keep saying something until people completely understand it The coach hammered his message into the team. → hammer→ See Verb table
Examples from the Corpus
hammer in• Even when she later encountered more difficulties, she tried all sorts of positions, but never changed her grip on the hammer.• Start a nail farther back from the end of the board and hammer it in at an angle toward the end.• The loss of Elliott left Hammer very lightweight in attack and placed a heavy burden on regular strikers White and Harris.• But her disappearance hammers home that in modern Britain, even a fleeting two minutes alone can put a child in danger.• Steam hammers, in short, tended to batter themselves to death.• This is because the center of gravity of the hammer is in the iron part.• Sybillin was last in action at Ascot last month when hammering seasoned handicappers in the Victor Chandler Chase. 