dominant

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

• adjective Exercising the most power, control, or influence.
• adjective Most abundant or conspicuous; predominant.
• adjective Higher; overlooking.
• adjective Tending to be stronger than its counterpart or used for the most important tasks or in the most pressing situations.
• adjective Genetics Of, relating to, or being an allele that produces the same phenotypic effect in heterozygotes as in homozygotes.
• adjective Ecology Of, relating to, or being a species that is most characteristic of an ecological community and usually determines the presence, abundance, and type of other species.
• adjective Music Relating to or based on the fifth tone of a diatonic scale.
• noun Genetics A dominant allele or a trait produced by a dominant allele.
• noun Ecology A dominant species.
• noun Music The fifth tone of a diatonic scale.

from The Century Dictionary.

• Exercising rule or chief authority; governing; predominant: as, the dominant party or faction.
• Hence Having a controlling effect or influence; most conspicuous or effective; overshadowing.
• noun In music: The reciting tone in Gregorian scales or modes.
• noun The fifth tone in the modern scales or modes: so called because of its importance in relation to the key-note or tonic.
• Having the crown free to light on all sides because of greater height. See crown *class.
• Characterized by or exhibiting dominance. See dominance, 2.
• noun In biology, when the cross-bred offspring of parents with antagonistic or mutually exclusive characters visibly exhibits a character of one parent, while it does not visibly exhibit but is able to transmit to descendants the antagonistic character of the other parent, then the character which is manifested, and the cross-bred organism
• noun which exhibits it, and
• noun those of its descendants which exhibit it, and
• noun the parental character, and
• noun the parent that exhibits it, are all called dominants.
• noun The greatest of a set of numbers without regard to sign.
• noun In petrography, in the quantitative classification (see rock), a factor which dominates over another between the ratios and .

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

• noun (Mus.) The fifth tone of the scale; thus G is the dominant of C, A of D, and so on.
• noun (Mus.) the chord based upon the dominant.
• adjective Ruling; governing; prevailing; controlling; predominant.
• adjective (Law) the estate to which a servitude or easement is due from another estate, the estate over which the servitude extends being called the servient estate or tenement.
• adjective (Law) one who owns lands on which there is an easement owned by another.

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

• noun music The fifth major tone of a musical scale (five major steps above the note in question); thus G is the dominant of C, A of D, and so on.
• noun music The triad built on the dominant tone.
• adjective Ruling; governing; prevailing; controlling; as, the dominant party, church, spirit, power.
• adjective Predominant, common, prevalent, of greatest importance.

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

• adjective exercising influence or control
• noun (music) the fifth note of the diatonic scale
• adjective most frequent or common
• adjective (of genes) producing the same phenotype whether its allele is identical or dissimilar
• noun an allele that produces the same phenotype whether its paired allele is identical or different