emperor

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The male ruler of an empire.
2. n. The emperor butterfly.
3. n. The emperor moth.

Century Dictionary and Cyclopedia

1. n. A commander-in-chief; a supreme leader of an army or of armies.
2. n. The sovereign or supreme ruler of an empire: a title of dignity conventionally superior to that of king: as, the emperor of Germany or of Russia. See empire. The title emperor, first assumed (with consent of the senate) by Julius Cæsar, was held by the succeeding rulers of the Roman, and afterward of the Western and Eastern empires. The line of emperors of the West terminated in a. d. 476, but the title was revived in 800 by Charlemagne, who thus laid the foundation of the elective Holy Roman Empire (which see, under empire). The last of his successors had, before his abdication in 1806, adopted the title of hereditary emperor of Austria. The king of Prussia was crowned emperor of Germany in 1871. Peter the Great of Russia assumed the title in 1721, and the ruler of Brazil in 1822; and it was held by Napoleon I. and Napoleon III. of France. In 1876 Queen Victoria of England was proclaimed empress of India. In western speech the sovereigns of Turkey, China, Japan, etc., are called emperors.
3. n. In zoöl.: In entomology: One of several large sphinxes or moths: as, the peacock emperor, Saturnia pavonia. One of several large butterflies of the family Nymphalidæ: as, the purple emperor, the popular name in Great Britain of Apatura iris, also called the purple high-flier; the tawny emperor, A. herse. See Apatura.
4. n. In ornithology, one of sundry birds notable of their kind.
5. n. A large boa of Central America, Boa imperator, probably a variety of the Boa constrictor.
6. n. Synonyms Monarch, etc. See prince.
7. n. [capitalized] The trade-name of a standard quality of fine English drawing-paper made in sheets 72 by 48 inches.

Wiktionary

1. n. The male monarch or ruler of an empire.

GNU Webster's 1913

1. n. The sovereign or supreme monarch of an empire; -- a title of dignity superior to that of king

WordNet 3.0

1. n. the male ruler of an empire
2. n. red table grape of California
3. n. large moth of temperate forests of Eurasia having heavily scaled transparent wings
4. n. large richly colored butterfly