sandbag vs strengthen

sandbag

verb
  • To conceal or misrepresent one's true position, potential, or intent in order to gain an advantage. 

  • To strike someone with a sandbag or other object to disable or render unconscious. 

  • To construct a barrier of sandbags around. 

  • To pretend to drink early on so that, as the night draws on, one can drink everybody else "under the table". 

  • To deceive someone by pretending to be weak, or (card games) by pretending to have a weak hand. 

noun
  • A sturdy sack filled with sand, generally used in large numbers to make defensive walls against flooding, bullets, or shrapnel. 

  • An engraver's leather cushion, etc. 

  • A small bag filled with sand and used as a cudgel. 

  • A deceptive play whereby a player with a strong hand bets weakly or passively. 

strengthen

verb
  • To substantiate; to corroborate (a belief, argument, etc.) 

  • To make strong or stronger; to add strength to; to increase the strength of; to fortify. 

  • To empower; to give moral strength to; to encourage; to enhearten. 

  • To reinforce, to add to, to support (someone or something) 

  • To grow strong or stronger. 

  • To augment; to improve; to intensify. 

How often have the words sandbag and strengthen occurred in a corpus of books? (source: Google Ngram Viewer )