strop1
  
  n.
 a device, typically a strip of leather, for sharpening razors.
v.
 (strops, stropping, stropped)
 sharpen on or with a strop.
 
  Etymology
  ME (in the sense ‘thong’, also as a naut. term): prob. a W. Gmc adoption of L. stroppus ‘thong’.
 
  
    
strop2
  
  n.
 Brit. informal a temper or bad mood.
 
  Etymology
  1970s: prob. a back-form. from stroppy.