1. buck up gain courage
  2. backstop a structure to prevent a ball from traveling out of a field
  3. backslap display excessive cordiality (towards)
  4. box up enclose or confine as if in a box
  5. duck soup any undertaking that is easy to do
  6. bucked up inspired with confidence
  7. backup the act of providing approval and support
  8. back up move backwards from a certain position
  9. backswept used of hair
  10. bucksaw a saw that is set in a frame in the shape of an H
  11. backspin spin that retards or reverses the forward motion
  12. pick up take and lift upward
  13. backside the side of an object that is opposite its front
  14. backseat a seat at the back of a vehicle
  15. backspace the typewriter key used for back spacing
  16. bookshop a shop where books are sold
  17. pickup the act or process of picking up or collecting from various places
  18. backstay a stay that supports the back of something
  19. backsaw a handsaw that is stiffened by metal reinforcement along the upper edge
  20. book up book all available places or tickets