balk

(noun) the area on a billiard table behind the balkline. Synonyms: baulk. Examples: "A player with ball in hand must play from the balk."

(noun) something immaterial that interferes with or delays action or progress. Synonyms: hindrance, hinderance, deterrent, impediment, baulk, check, handicap.

(noun) one of several parallel sloping beams that support a roof. Synonyms: rafter, baulk.

(noun) an illegal pitching motion while runners are on base.

(verb) refuse to comply. Synonyms: resist, baulk, jib.