Noun

1. A slender, straight, sharply pointed sword (double-edged, single-edged or edgeless).
   • , act IV scene 1

     […] In his lawless fit,

     Behind the arras hearing something stir,

     Whips out his rapier, cries ‘A rat, a rat!’

     And in this brainish apprehension kills

     The unseen good old man.

Adjective

1. Extremely sharp

   That knife is very rapier.

2. Cutting smarts or keen wit.

   John is very quick on his feet during interviews by using his rapier responses.