From rare Middle English strengthenen (14th c.), from earlier strengthen (12th c.), where -en is the infinitive ending. Probably the original form was reinterpreted as strength +‎ -en around the time when the infinitive ending was being apocopated in late Middle English.


  • IPA(key): /ˈstɹɛŋ(k)θən/
  • (file)


strengthen (third-person singular simple present strengthens, present participle strengthening, simple past and past participle strengthened)

  1. (transitive) To make strong or stronger; to add strength to; to increase the strength of; to fortify.
    strengthen a muscle
    strengthen a wall
    strengthen an army
    strengthen one's willpower
    strengthen one's authority
    • c. 1600, William Shakespeare, Henry IV, Part 2
      Let noble Warwick, Cobham, and the rest, []
      With powerful policy strengthen themselves.
    • 1851, Anonymous, Arthur Hamilton, and His Dog
      A little hardship, and a little struggling with the rougher elements of life, will perchance but strengthen and increase his courage, and prepare him for the conflicts and struggles of after years.
  2. (transitive) To empower; to give moral strength to; to encourage; to enhearten.
    • 1831, Nat Turner, The Confessions of Nat Turner:
      my father and mother strengthened me in this my first impression, saying in my presence, I was intended for some great purpose
    • 1769, The King James Bible, Deuteronomy iii. 28
      Charge Joshua, and encourage him, and strengthen him.
    • 1910, Emerson Hough, chapter I, in The Purchase Price: Or The Cause of Compromise, Indianapolis, Ind.: The Bobbs-Merrill Company, OCLC 639762314, page 0124:
      "A fine man, that Dunwody, yonder," commented the young captain, as they parted, and as he turned to his prisoner. "We'll see him on in Washington some day. He is strengthening his forces now against Mr. Benton out there. []."
  3. (transitive) To augment; to improve; to intensify.
  4. (intransitive) To grow strong or stronger.
    • 1914, Elizabeth Robins Pennell, Our Philadelphia:
      my affection seems so superfluous that I often wonder why it should be so strong. But wise or foolish, there it is, strengthening with the years whether I will or no



Derived termsEdit