slope vs declination

slope and declination both are nouns.

Word	Noun	Adjective	Verb	Adverb
slope	Yes	No	Yes	No
declination	Yes	No	No	No

As nouns, declination is a hyponym of slope; that is, declination is a word with a more specific, narrower meaning than slope:

slope (noun)	declination (noun)
the property possessed by a line or surface that departs from the horizontal	a polite refusal of an invitation
an elevated geological formation	(astronomy) the angular distance of a celestial body north or to the south of the celestial equator; expressed in degrees; used with right ascension to specify positions on the celestial sphere
	a downward slope or bend
	a condition inferior to an earlier condition; a gradual falling off from a better state; decline

slope (verb)	declination (verb)
be at an angle