Emily Dickinson Lexicon

MATE, n.¹ [D. maat; Ar. مَطَا matau, to associate. Class Md, No. 11.]

1. A companion; an associate; one who customarily associates with another. Young persons nearly of an age, and frequently associating, are called mates or playmates.
2. A husband or wife.
3. The male or female of animals which associate for propagation and the care of their young. Milton.
4. One that eats at the same table.
5. One that attends the same school; a school-mate.
6. An officer in a merchant ship or ship of war, whose duty is to assist the master or commander. In a merchant ship, the mate, in the absence of the master, takes command of the ship. Large ships have a first, second and third mate. In general, mate, in compound words, denotes an assistant, and ranks next in subordination to the principal; as master's mate; surgeon's mate, &c.