vertical tail: the vertical airfoil in the tail assembly of an aircraft
airfoil: a device that provides reactive force when in motion relative to the surrounding air; can lift or control a plane in flight
regression coefficient: 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