What are the antonyms for Laxing?

• v.

  • loosen
  • attach
  ,
  • button
  ,
  • combine
  ,
  • confine
  ,
  • connect
  ,
  • couple
  ,
  • detain
  ,
  • engage
  ,
  • fasten
  ,
  • hitch
  ,
  • hold
  ,
  • hook
  ,
  • imprison
  ,
  • incarcerate
  ,
  • join
  ,
  • keep
  ,
  • limit
  ,
  • link
  ,
  • restrain
  ,
  • unite
  .
  • relax
  • agitate
  ,
  • excite
  ,
  • grow
  ,
  • incite
  ,
  • increase
  ,
  • intensify
  ,
  • raise
  ,
  • rise
  ,
  • strengthen
  ,
  • tense
  ,
  • worry
  .
  • slack/slacken
  • stiffen
  ,
  • tighten
  .

Well up on is typically used to describe someone who possesses a great amount of knowledge or expertise on a particular subject. However, there are several antonyms for this phrase...