Definitions of nut:

• noun:   a small (usually square or hexagonal) metal block with internal screw thread to be fitted onto a bolt
• noun:   Egyptian goddess of the sky
• noun:   usually large hard-shelled seed
• noun:   someone who is so ardently devoted to something that it resembles an addiction

  Example: "A car nut"

• noun:   half the width of an em
• noun:   a whimsically eccentric person
• noun:   one of the two male reproductive glands that produce spermatozoa and secrete androgens
• verb:   gather nuts