tap1
  
  n.
     - a device by which a flow of liquid or gas from a pipe or container can be controlled.
 - an instrument for cutting a threaded hole in a material.
 - a device connected to a telephone for listening secretly to conversation.
 - 
(also tapping)
 Brit. an electrical connection made to some point between the end terminals of a transformer coil or other component.
 - Brit. a taproom.
 
v.
 (taps, tapping, tapped)
     - draw liquid through the tap or spout of (a cask, barrel, etc.).
 - draw sap from (a tree) by cutting into it.
 - exploit or draw a supply from (a resource). 
▸informal obtain money or information from.
 - connect a device to (a telephone) so that conversation can be listened to secretly.
 - cut a thread in (something) to accept a screw.
 
 
  Phrase
  
    
      - on tap
  - ready to be poured from a tap. 
▸informal freely available whenever needed.
 - N. Amer. informal on schedule to occur.
 
 
    
   
  Derivative
  
  Etymology
  OE tæppa ‘stopper for a cask’, tæppian ‘provide (a cask) with a stopper’, of Gmc origin.
 
  
    
tap2
  
  v.
 (taps, tapping, tapped)
   - strike or knock with a quick light blow or blows. 
▸strike lightly and repeatedly against something else:
 she was tapping her feet.
 - 
(tap someone up)
 Brit. informal approach (a sports player) illegally with a view to signing them to another club while they are still under contract with their current one.
 - N. Amer. informal designate or select for a task or honour.
 
n.
   - a quick light blow or the sound of such a blow.
 - tap dancing. 
▸a piece of metal attached to the toe and heel of a tap dancer's shoe to make a tapping sound.
 - 
(taps)
 
[treated as sing. or pl.]
 US a bugle call for lights to be put out in army quarters. 
▸a similar call sounded at a military funeral.
 ▸Brit. (in the Guide movement) a closing song sung at an evening camp fire or at the end of a meeting.
 
 
  Derivative
  
  Etymology
  ME: from OFr. taper, or of imitative origin; cf. clap1 and rap1.