1. baseline, standard, criterion, measure, touchstone

usage: an imaginary line or standard by which things are measured or compared; "the established a baseline for the budget"

2. service line, baseline, line

usage: the back line bounding each end of a tennis or handball court; when serving the server must not step over this line

3. baseline, line

usage: the lines a baseball player must follow while running the bases

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See also: baseline (Dictionary)