def

/dɛf/
adjective
  1. Excellent, cool, or impressive (slang).
    • He wore a def outfit to the concert last night.
    • The party was def — everyone had a great time.
    • That new song is totally def!
adverb
  1. Short for 'definitely'; certainly or without doubt (informal).
    • She def knows the answer to that question.
    • I def want to go to the beach this weekend.
    • We are def going to win the game tonight.
What does "def" mean? | whatsthatwordmean | whatsthatwordmean