Main Entry: base·line

Pronunciation: \ˈbās-ˌlīn\

Function: noun

Usage: often attributive

Date: 1610

1 : a line serving as a basis; especially : one of known measure or position used (as in surveying or navigation) to calculate or locate something
2 a : either of the lines on a baseball field that lead from home plate to first base and third base and 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 usually initial set of critical observations or data used for comparison or a control
5 : a starting point <the baseline of this discussion>