Definitions of tread:

• noun:   structural member consisting of the horizontal part of a stair or step
• noun:   the part (as of a wheel or shoe) that makes contact with the ground
• noun:   the grooved surface of a pneumatic tire
• noun:   a step in walking or running
• verb:   apply (the tread) to a tire
• verb:   brace (an archer's bow) by pressing the foot against the center
• verb:   mate with

  Example: "Male birds tread the females"

• verb:   crush as if by treading on

  Example: "Tread grapes to make wine"

• verb:   tread or stomp heavily or roughly
• verb:   put down or press the foot, place the foot

  Example: "For fools rush in where angels fear to tread"