chief

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One who is highest in rank or authority; a leader.
• noun A chief petty officer.
• noun Nautical The chief engineer of a ship.
• noun Slang A supervisor; a boss.
• noun Heraldry The upper section of a shield.
• adjective Highest in rank, authority, or office.
• adjective Most important or influential.

from The Century Dictionary.

• noun The senior general-staff officer on the staff of the commander of an army, army-corps, division, or department.
• noun The senior officer on the personal staff of a flag-officer in command of a fleet or squadron. When practicable, he is senior in rank to all other officers under command of the flag-officer.
• Chiefly. Thomson.
• noun A head; the head or upper part of anything.
• noun The person highest in authority; the head or head man.
• noun A principal, leader, or director in general; especially, the hereditary or the chosen head of a clan or tribe: used as a title particularly for the heads of Scottish Highland clans, and for the controlling or governing heads of uncivilized or semi-civilized tribes.
• noun The principal officer of a bureau or division of the civil service, or of an editorial staff, newspaper office, mercantile establishment, or other organized body.
• noun The principal or most important part or portion; the bulk or larger part of one thing or of many.
• noun In heraldry, the head or upper part of the escutcheon, from side to side, cut off horizontally by a straight line, and containing properly a third part of the dimensions of the escutcheon.
• noun The prime; the most important part.
• noun At the head; in the principal or highest position or office: as, the commander-in-chief.
• noun In heraldry, charged upon the upper part of the shield: a term generally used when the chief itself is not indicated
• noun Directly: said of land tenure: as, to hold land in chief (to hold it directly from the sovereign by honorable personal services).
• noun In direct or original procedure: as, an examination in chief. See examination.
• noun Synonyms Chief, Chieftain, Commander, Leader, Head, Chief, literally the head, is applied to one who occupies the highest rank in military or civil matters: as, an Indian chief; a military chief; the chief of a department in the civil service; a party chief. Chieftain is now mostly poetic, and is sometimes used in prose where the leadership is peculiarly suggestive of the past: as, a Highland chieftain. A commander is one who issues commands to a body or organization of a military or naval character, or has authority over it: as, the commander of the army in the East; the commander of the Asiatic squadron. A leader is the head of a party or faction, or one who conducts some special undertaking, perhaps actually going at the head: as, the leader of the House of Commons; the leader of the Conservative or Republican party; the leader of the storming party or forlorn hope; a leader of fashion. Head is applied to the chief of a tribe or family or profession: as, the head of the house of Cavendish; the head of the church; the head of the bar.
• Highest in office, authority, rank, or estimation; placed above the rest; principal: as, a chief priest; the chief butler.
• Hence— Principal or most eminent, in any quality or action; such that others (things, persons, particulars of any kind) are by comparison inferior or subordinate; most important; leading; main; most conspicuous.
• Intimate; near; close.
• Synonyms First, paramount, supreme, cardinal, capital, prime, vital, especial, essential, great, grand.

from the GNU version of the Collaborative International Dictionary of English.

• noun The head or leader of any body of men; a commander, as of an army; a head man, as of a tribe, clan, or family; a person in authority who directs the work of others; the principal actor or agent.
• noun The principal part; the most valuable portion.
• noun (Her.) The upper third part of the field. It is supposed to be composed of the dexter, sinister, and middle chiefs.
• noun (Eng. Law) From the king, or sovereign.
• adjective Highest in office or rank; principal; head.
• adjective Principal or most eminent in any quality or action; most distinguished; having most influence; taking the lead; most important.
• adjective obsolete Very intimate, near, or close.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun An informal address to an equal.
• adjective Primary; principal.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the head of a tribe or clan
• adjective most important element
• noun a person who is in charge
• noun a person who exercises control over workers