rectilinear regression vs regression coefficient

rectilinear regression and regression coefficient both are nouns.

Word	Noun	Adjective	Verb	Adverb
rectilinear regression	Yes	No	No	No
regression coefficient	Yes	No	No	No

rectilinear regression (noun)	regression coefficient (noun)
the relation between variables when the regression equation is linear: e.g., y = ax + b	when the regression line is linear (y = ax + b) the regression coefficient is the constant (a) that represents the rate of change of one variable (y) as a function of changes in the other (x); it is the slope of the regression line