tick3
  
  n.
 
(
in phr. on tick)
 on credit.
Etymology
  C17: appar. short for ticket in the phr. on the ticket, referring to a promise to pay.
 
  
    
tick4
  
  n.
 a fabric case stuffed with feathers or other material to form a mattress or pillow. 
▸short for ticking.
Etymology
  ME: prob. Mid. Low Ger., MDu. tēke, or MDu. tīke, via W. Gmc from L. theca ‘case’, from Gk thēkē.