remarkable vs singular

remarkable is not a noun while singular is a noun.

Word	Noun	Adjective	Verb	Adverb
remarkable	No	Yes	No	No
singular	Yes	Yes	No	No

As adjectives, remarkable and singular are synonyms defined as:

remarkable (noun)	singular (noun)
	the form of a word that is used to denote a singleton

remarkable (adjective)	singular (adjective)
unusual or striking	grammatical number category referring to a single item or unit
worthy of attention	composed of one member, set, or kind
	unusual or striking
	being a single and separate person or thing
	the single one of its kind
	beyond or deviating from the usual or expected