sunk fence vs ha-ha

sunk fence and ha-ha both are nouns.

Word	Noun	Adjective	Verb	Adverb
sunk fence	Yes	No	No	No
ha-ha	Yes	No	No	No

As nouns, sunk fence and ha-ha are synonyms defined as:

sunk fence and ha-ha: a ditch with one side being a retaining wall; used to divide lands without defacing the landscape

Other synonyms of sunk fence include haw-haw.

sunk fence (noun)	ha-ha (noun)
a ditch with one side being a retaining wall; used to divide lands without defacing the landscape	a ditch with one side being a retaining wall; used to divide lands without defacing the landscape
	a loud laugh that sounds like a horse neighing