dominant
1. (in genetics) Describing the allele that is expressed in the phenotype when two different alleles of a gene are present in the cells of an organism. For example, the height of garden peas is controlled by two alleles, ‘tall’ (T) and ‘dwarf’ (t). When both are present (Tt), i.e. when the cells are heterozygous, the plant is tall since T is dominant and t is recessive. See also codominance; incomplete dominance.

2. (in ecology) Describing the most conspicuously abundant and characteristic species in a community. The term is usually used of a plant species in plant ecology; for example, pine trees in a pine forest.

3. (in animal behaviour) Describing an animal that is allowed priority in access to food, mates, etc., by others of its species because of its success in previous aggressive encounters. Less dominant animals frequently show appeasement behaviour towards a more dominant individual, so overt aggression is minimized. In a stable group there may be a linear dominance hierarchy or peck order (so called because it was first observed in domestic fowl), with each animal being subservient to those above it in the hierarchy and taking precedence over those below it.

dom·i·nant / ˈdämənənt/ • adj. most important, powerful, or influential: they are now in an even more dominant position in the market. ∎  (of a high place or object) overlooking others. ∎  Genetics relating to or denoting heritable characteristics that are controlled by genes that are expressed in offspring even when inherited from only one parent. Often contrasted with recessive. ∎  Ecol. denoting the predominant species in a plant (or animal) community. ∎  in decision theory, (of a choice) at least as good as the alternatives in all circumstances, and better in some: holding back is here a dominant strategy.• n. a dominant thing, in particular: ∎  Genetics a dominant trait or gene. ∎  Ecol. a dominant species in a plant (or animal) community. ∎  Mus. the fifth note of the diatonic scale of any key, or the key based on this, considered in relation to the key of the tonic.DERIVATIVES: dom·i·nant·ly adv.

dominant.
1. 5th degree of major or minor scale, thus if the key is B (major or minor) the dominant is F♯. Chords built on this note are dominant chords, the most important being the dominant seventh which is a chord consisting of the common chord of the dominant with the minor 7th from its root added, e.g. in key C it is G–B–D–F. Like all intervals of a 7th, the dominant 7th is a discord. It normally resolves on the tonic or submediant chord, the note constituting the 7th falling a semitone, allowing the 3rd (i.e. the leading note of the scale) to rise to the tonic. More rarely the 7th can remain as a note common to the following chord, usually the 1st or 2nd inversion of the subdominant. The three inversions of the dominant seventh chord are, of course, in common use.

2. See modes.

dominant ruling, commanding XV; (mus.) (pert. to) the fifth note of the scale of any key XIX. — (O)F. — L. domināns, -ant-, prp. of dominārī (f. dominus), on the pp. stem of which was formed dominate XVII; see DOM, -ANT, -ATE 3.
So domination XIV. -(O)F. — L.

dominant (dom-i-nănt) adj. (in genetics) describing a gene (or its corresponding characteristic) whose effect is shown in the individual whether its allele is the same or different. autosomal d. see autosomal (dominant). Compare recessive.
—dominant n.