odd vs leftover

odd is not a noun while leftover is a noun.

Word	Noun	Adjective	Verb	Adverb
odd	No	Yes	No	No
leftover	Yes	Yes	No	No

As adjectives, odd and leftover are synonyms defined as:

Other synonyms of odd include left, left over, remaining, unexpended.

odd (noun)	leftover (noun)
	a small part or portion that remains after the main part no longer exists

odd (adjective)	leftover (adjective)
not divisible by two	not used up
an indefinite quantity more than that specified
of the remaining member of a pair
beyond or deviating from the usual or expected
not used up
not easily explained