What is Master?

Legal Definition
This word has several meanings. 1. Master is one who has control over a servant or apprentice. A master stands in relation to his apprentices, in loco parentis, and is bound to fulfil that relation, which the law generally enforces. He is also entitled to be obeyed by his apprentices, as if they were his children. Bouv. Inst. Index, h. t.

2. - 2. Master is one who is employed in teaching children, known generally as a schoolmaster; as to his powers, see Correction.

3. - 3. Master is the name of an officer: as, the ship Benjamin Franklin, whereof A B is master; the master of the rolls; master in chancery, &c.

4. - 4. By master is also understood a principal who employs another to perform some act or do something for him. The law having adopted the maxim of the civil law, qui facit per alium facit per se; the agent is but an instrument, and the master is civilly responsible for the act of his agent, as if it were his own, when he either commands him to do an act, or puts him in a condition, of which such act is a result, or by the absence of due care and control, either previously in the choice of his agent, or immediately in the act itself, negligently suffers him to do an injury. Story, Ag. 454, note; Noy's Max. c. 44; Salk. 282; 1 East. R. 106; 1 Bos. & Pul. 404; 2 H. Bl. 267; 5 Barn. & Cr. 547; 2 Taunt. R. 314; 4 Taunt. R. 649; Mass. 364, 385; 17 Mass. 479, 509; 1 Pick. 47 5; 4 Watts, 222; 2 Harr. & Gill, 316; 6 Cowen, 189; 8 Pick. 23; 5 Munf. 483. Vide Agent; Agency; Driver; Servant.
-- Bouviers Law Dictionary
Legal Definition
One having authority; one who rules, directe, instructs or superintends ; a head or chief; an instructor; an employer. Applied to several judicial officers. See infra.
-- Black's Law Dictionary
Legal Definition
One who stands in such relation to another that he not only controls the result of the other’s work, but may also direct the manner of the doing of it. See 214 Pa. St. 229; 112 Am. St. Rep. 739, fi L. R. A. (N. S.) 544, 63 Atl. 792. Also a Master in chancery, which see.
-- Ballentine's Law Dictionary