What does allel mean?
An allel is a variant spelling of 'allele', a foundational concept in genetics referring to one of two or more alternative forms of a gene that sit at the same position, or locus, on paired chromosomes. Because organisms typically inherit one copy of each gene from each parent, an individual may carry two identical copies of an allel (homozygous) or two different ones (heterozygous), with the interaction between them shaping observable traits such as flower colour or blood type. The term entered science through early twentieth-century Mendelian research and remains central to discussions of inheritance, variation, and disease. In practice, however, 'allel' is uncommon in modern English texts; standard scientific literature uses the fuller spelling 'allele'. Encountering this shorter form usually signals a German-language source, a translation, or older continental European terminology rather than a distinct meaning.
nounA variant form of 'allele': one of two or more alternative forms of a gene that occupy the same position (locus) on homologous chromosomes and determine contrasting traits.
- One of the alternative forms of a gene occupying a given locus on a chromosome.
"The dominant allel masked the expression of its recessive partner."
"In classical Mendelian experiments, each parent contributed one allel for every hereditary trait."
"The heterozygote carried a dominant allel alongside a recessive one."
When used at all, the plural follows regular noun inflection; note that the standard-spelled plural 'alleles' vastly predominates in scientific writing.
"Diploid organisms carry two allels of most genes, one per chromosome."
Drop one letter from 'allele' and you get the spelling German geneticists have used for over a century — same gene, different orthography.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of allel
The word derives from the German 'Allel', an abbreviation coined by geneticists from 'allelomorph' (from Greek 'allēlōn', meaning 'of one another'), which William Bateson introduced around 1902 to describe contrasting gene pairs. As Mendelian genetics spread internationally in the early twentieth century, English adopted the expanded forms 'allele' and 'allelic'. The shortened 'allel' persists mainly in German scientific usage and as a combining element in English derivatives such as 'allelism' and 'allelotype'.
Related word forms
How allel is actually used
This spelling is rare in contemporary English; scientific writing overwhelmingly uses 'allele'. Readers encountering 'allel' are most likely reading translated or older European sources.
Easily confused with allel
'Allele' is the standard English spelling; 'allel' is an uncommon variant chiefly seen in German-language genetics literature.