Definitions of balk:

• noun:   an illegal pitching motion while runners are on base
• noun:   the area on a billiard table behind the balkline

  Example: "A player with ball in hand must play from the balk"

• noun:   one of several parallel sloping beams that support a roof
• noun:   something immaterial that interferes with or delays action or progress
• verb:   refuse to comply
• name:  A surname (rare: 1 in 100000 families; popularity rank in the U.S.: #15929)