allele

noun

al·​lele ə-ˈlēl 

1

: any of the alternative forms of a gene that may occur at a given locus (see locus sense 3)

2

: either of a pair of alternative Mendelian characters (see character entry 1 sense 1c(2)) (such as smooth and wrinkled seed in the pea)

allelic

ə-ˈlē-lik 

-ˈle-

adjective

allelism

ə-ˈlē-ˌli-zəm 

-ˈle-

noun

Examples of allele in a Sentence

Recent Examples on the Web

Together, these two studies show us that some aspects of blood type variation (like the O allele) emerged later in evolutionary history, within the human lineage and our close relatives. —Scott Travers, Forbes.com, 20 Apr. 2026

The gene has several versions, or alleles: APOE2, APOE3, and APOE4. —New Atlas, 26 Oct. 2025

Most people who acquire type 1 diabetes have at least one of two specific-risk-conferring gene variants, or alleles, in this region. —Rachel Nuwer, Scientific American, 14 Oct. 2025

Cahn said that, for each gene, a cat inherits one copy, called an allele, from each parent. —Maria Azzurra Volpe, MSNBC Newsweek, 16 June 2025

Word History

Etymology

perhaps as back-formation from allelism, from allel- (in allelomorph) + -ism

First Known Use

1921, in the meaning defined at sense 1

Phrases Containing allele

• multiple allele

Kids Definition

allele

noun

al·​lele ə-ˈlē(ə)l 

: one of several forms of a gene that determine alternate forms of one or more genetic traits and occupy identical places on two chromosomes having the same genes arranged in the same order

allelic

-ˈlē-lik 

-ˈlel-ik

adjective

Medical Definition

allele

noun

al·​lele ə-ˈlē(ə)l 

1

: any of the alternative forms of a gene that may occur at a given locus

2

: either of a pair of alternative Mendelian characters (as ability versus inability to taste the chemical phenylthiocarbamide)

allelic

-ˈlē-lik  -ˈlel-ik 

adjective

allelism

-ˈlē(ə)l-ˌiz-əm  -ˈlel-ˌiz- 

noun