lubber's point vs lubber's mark

lubber's point and lubber's mark both are nouns.

Word	Noun	Adjective	Verb	Adverb
lubber's point	Yes	No	No	No
lubber's mark	Yes	No	No	No

As nouns, lubber's point and lubber's mark are synonyms defined as:

lubber's point and lubber's mark: a fixed line on a ship's compass indicating its heading

Other synonyms of lubber's point include lubber's line, lubber line.

lubber's point (noun)	lubber's mark (noun)
a fixed line on a ship's compass indicating its heading	a fixed line on a ship's compass indicating its heading