centerboard vs centreboard

centerboard and centreboard both are nouns.

Word	Noun	Adjective	Verb	Adverb
centerboard	Yes	No	No	No
centreboard	Yes	No	No	No

As nouns, centerboard and centreboard are synonyms defined as:

centerboard and centreboard: a retractable fin keel used on sailboats to prevent drifting to leeward

Other synonyms of centerboard include drop keel, sliding keel.

centerboard (noun)	centreboard (noun)
a retractable fin keel used on sailboats to prevent drifting to leeward	a retractable fin keel used on sailboats to prevent drifting to leeward