baulk vs millstone

baulk and millstone both are nouns.

Word	Noun	Adjective	Verb	Adverb
baulk	Yes	No	Yes	No
millstone	Yes	No	No	No

As nouns, millstone is a hyponym of baulk; that is, millstone is a word with a more specific, narrower meaning than baulk:

baulk: something immaterial that interferes with or delays action or progress
millstone: (figurative) something that hinders or handicaps

Other hyponyms of baulk include albatross, bind, diriment impediment, drag, obstacle, obstruction, straitjacket.

baulk (noun)	millstone (noun)
one of several parallel sloping beams that support a roof	one of a pair of heavy flat disk-shaped stones that are rotated against one another to grind the grain
something immaterial that interferes with or delays action or progress	any load that is difficult to carry
the area on a billiard table behind the balkline	(figurative) something that hinders or handicaps

baulk (verb)	millstone (verb)
refuse to comply