[base.line] n, often attrib (1750) 1: a line serving as a basis; esp: one of known measure or position used (as in surveying or navigation) to calculate or locate something
2. a: either of the lines leading from home plate to first base and third base that are extended into the outfield as foul lines b: base path
3: a boundary line at either end of a court (as in tennis or basketball)
4: a set of critical observations or data used for comparison or a control
5: a starting point "the ~ of this discussion"