late 14c., "act of planting or fixing in the ground," verbal noun from pitch (v.1). From 1650s as "act of throwing or hurling;" specifically in baseball by 1858.
Entries linking to pitching
c. 1200, "to thrust (something) in, drive (a stake), pierce with a sharp point," senses now obsolete, also "to fasten, settle," probably from an unrecorded Old English *piccean, related to prick (v.). The original past tense was pight.
The sense of "set upright" (mid-13c.) as in pitch a tent (late 13c.), is from the notion of driving or thrusting the pegs into the ground. The meaning "incline forward and downward" is from 1510s. The intransitive sense of "to plunge or fall headlong" is by 1680s, probably from the use with reference to ships (see below) extended to persons, animals, etc.
The meaning "to throw, fling, hurl, toss" (a ball, a person, hay, etc.) evolved by late 14c. from that of "hit the mark." Specifically in baseball, "to hurl (the ball) to the batter," by 1868.
Musical sense of "determine or set the key of" is by 1630s. Of ships, "to plunge with alternate fall and rise of the bow and stern" as in passing over waves, 1620s.
To pitch in "work vigorously" is from 1847, perhaps from farm labor. A pitched battle is one in which the armies are previously drawn up in form, with a regular disposition of the forces (from the verb in the sense of "to fix or set in order, arrange," late 15c.). Related: Pitched.