variable vs North Star

variable and North Star both are nouns.

Word	Noun	Adjective	Verb	Adverb
variable	Yes	Yes	No	No
North Star	Yes	No	No	No

variable (noun)	North Star (noun)
a quantity that can assume any of a set of values	the brightest star in Ursa Minor; at the end of the handle of the Little Dipper; the northern axis of the earth points toward it
a symbol (like x or y) that is used in mathematical or logical expressions to represent a variable quantity
something that is likely to vary; something that is subject to variation
a star that varies noticeably in brightness

variable (adjective)	North Star (adjective)
liable to or capable of change
(used of a device) designed so that a property (as e.g. light) can be varied
marked by diversity or difference