rival

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

• noun One who attempts to equal or surpass another, or who pursues the same object as another; a competitor.
• noun One that equals or almost equals another in a particular respect.
• noun Obsolete A companion or an associate in a particular duty.
• intransitive verb To attempt to equal or surpass.
• intransitive verb To be the equal of; match.
• intransitive verb To be a competitor or rival; compete.

from The Century Dictionary.

• To stand in competition with; seek to gain something in opposition to: as, to rival one in love.
• To strive to equal or excel; emulate.
• To be a competitor; act as a rival.
• noun One having a common right or privilege with another; an associate; an alternating partner or companion in duty.
• noun One who is in pursuit of the same object as another; one who strives to reach or obtain something which another is attempting to obtain, and which only one can possess; a competitor: as, rivals in love; rivals for a crown.
• noun One who emulates or strives to equal or exceed another in excellence; a competitor; an antagonist: as, two rivals in eloquence.
• noun Synonyms and See emulation.
• Having the same pretensions or claims; standing in competition for superiority: as, rival lovers; rival claims or pretensions.

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

• noun obsolete A person having a common right or privilege with another; a partner.
• noun One who is in pursuit of the same object as another; one striving to reach or obtain something which another is attempting to obtain, and which one only can posses; a competitor
• adjective Having the same pretensions or claims; standing in competition for superiority
• transitive verb To stand in competition with; to strive to gain some object in opposition to.
• transitive verb To strive to equal or exel; to emulate.
• intransitive verb obsolete To be in rivalry.

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

• noun A competitor (person, team, company, etc.) who is well known to another and has similar skills and achievements. Defeating a rival may be a primary or necessary goal of a competitor.
• noun Someone or something with similar claims of quality or distinction as another.
• verb transitive To oppose or compete with.
• verb To equal to or surpass another.

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

• verb be the rival of, be in competition with
• noun the contestant you hope to defeat
• verb be equal to in quality or ability