Neckline
The opening of a garment around the neck, and the shape of its edge on the pattern.
The width and depth of the neckline define the style (round, V, square, boat) and the fit around the neck and shoulders. On the pattern it is drawn on both the front and the back pieces and has to match at the shoulder seams. It is finished with a facing, a binding or a collar, and in knits it is graded carefully because the stretch changes how it sits.
Example
A round neckline can be deepened at the front by lowering the center-front point, while the back neckline stays shallower.