(music) the fifth note of the diatonic scale
"In jazz harmony, musicians often substitute a dominant seventh chord built on the fifth degree to create strong tension before resolving back home."
an allele that produces the same phenotype whether its paired allele is identical or different
"In Mendelian genetics, the brown eye color allele acts as a dominant trait because it results in brown eyes regardless of whether the other allele is also brown or for blue."
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.
"In the key of C major, the note G functions as the dominant, creating tension that resolves back to the tonic."
In plain English: A dominant is someone who acts as if they are more important than everyone else around them.
"In this family, he is the dominant force who makes all the final decisions."
Usage: As a noun, "dominant" refers specifically to the fifth degree of a musical scale. Use this term only when discussing music theory contexts involving tonal relationships.
exercising influence or control
"television plays a dominant role in molding public opinion"
"the dominant partner in the marriage"
(of genes) producing the same phenotype whether its allele is identical or dissimilar
"The dominant gene ensures that every offspring displays the purple flower trait, regardless of whether it inherited a matching or different version from its parent."
Ruling; governing; prevailing
"The dominant culture in the region has traditionally shaped local customs and values."
In plain English: Dominant means being more powerful, important, or noticeable than everything else around you.
"The dominant color in her new outfit is bright yellow."
The word entered English from Middle French as dominant. It originally described something that dominates or holds power over others.