Definition of baselines:
(n) :
A datum used as the basis for calculation or for comparison.
(n) :
A line that is a base for measurement or for construction.
(n) :
(engineering) A configuration of software, hardware, or a process that is established and documented as a point of reference.
(n) :
(typography) A line used as the basis for the alignment of glyphs.
(n) :
(tennis) The line at the farthest ends of the court indicating the boundary of the area of play.
(v) :
(engineering, computing) To provide a baseline for measurement.