aid vs sustain

aid

verb
  • To provide support to; to further the progress of; to help; to assist. 

  • To climb with the use of aids such as pitons. 

noun
  • Help; assistance; succor, relief. 

  • An historical subsidy granted to the crown by Parliament for an extraordinary purpose, such as a war effort. 

  • A helper; an assistant. 

  • An exchequer loan. 

  • Something which helps; a material source of help. 

  • A pecuniary tribute paid by a vassal to his feudal lord on special occasions. 

  • The rider's use of hands, legs, voice, etc. to control the horse. 

sustain

verb
  • To aid, comfort, or relieve; to vindicate. 

  • To provide for or nourish. 

  • To encourage or sanction (something). 

  • To maintain, or keep in existence. 

  • To allow, accept, or admit (e.g. an objection or motion) as valid. 

  • To keep from falling; to bear; to uphold; to support. 

  • To confirm, prove, or corroborate; to uphold. 

  • To experience or suffer (an injury, etc.). 

noun
  • A mechanism which can be used to hold a note, as the right pedal on a piano. 

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