linear function vs linear regression

linear function and linear regression both are nouns.

Word	Noun	Adjective	Verb	Adverb
linear function	Yes	No	No	No
linear regression	Yes	No	No	No

linear function (noun)	linear regression (noun)
a mathematical function whose graph (in Cartesian coordinates with uniform scales) is a line in the plane.	the relation between variables when the regression equation is linear: e.g., y = ax + b