unsuccessful vs weak

unsuccessful

adj
  • Failed, not successful. 

weak

adj
  • Not prevalent or effective, or not felt to be prevalent; not potent; feeble. 

  • That does not ionize completely into anions and cations in a solution. 

  • Not having power to convince; not supported by force of reason or truth; unsustained. 

  • Lacking in vigour or expression. 

  • Unable to sustain a great weight, pressure, or strain. 

  • Definite in meaning, often used with a definite article or similar word. 

  • One of the four fundamental forces associated with nuclear decay. 

  • Dilute, lacking in taste or potency. 

  • Showing less distinct grammatical endings. 

  • Having a narrow range of logical consequences; narrowly applicable. (Often contrasted with a strong statement which implies it.) 

  • Tending towards lower prices. 

  • Lacking in force (usually strength) or ability. 

  • Unable to withstand temptation, urgency, persuasion, etc.; easily impressed, moved, or overcome; accessible; vulnerable. 

  • Bad or uncool. 

  • Regular in inflection, lacking vowel changes and having a past tense with -d- or -t-. 

  • Resulting from, or indicating, lack of judgment, discernment, or firmness; unwise; hence, foolish. 

  • Lacking contrast. 

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