verb (v)

• straighten up or out; make straight(verb.motion)

  Synonym:
  unbend
  Antonym:
  bend, flex
  

  source: wordnet30
• make straight(verb.contact)

  Synonym:
  straighten out
  

  source: wordnet30
• get up from a sitting or slouching position(verb.motion)

  Example:
  The students straightened when the teacher entered.
  

  source: wordnet30
• put (things or places) in order(verb.change)

  Synonym:
  clean up, neaten, square away, straighten out, tidy, tidy up
  

  source: wordnet30
• straighten by unrolling(verb.contact)

  Synonym:
  roll out
  

  source: wordnet30
• make straight or straighter(verb.change)

  Example:
  Straighten this post.
  Straighten hair.
  

  source: wordnet30
• To make straight; to reduce from a crooked to a straight form.(verb)

  source: webster1913
• A variant of Straiten.(verb)

  source: webster1913