1) Cistron 2) Factor 3) Gene 
Used of genes that are not competitors at the same locus; how independently they will behave depends on whether their loci are linked. At least when first formed (for instance, as a result of unequal crossing-over) two nonalleles may be identical. ... (05 Mar 2000) ... 
Type: Term Pronunciation: non′ă-lēl′ Definitions: 1. Used of genes that are not competitors at the same locus; how independently they will behave depends on whether their loci are linked. At least when first formed (for instance, as a result of unequal crossing-over), two nonalleles may be identical.
[n] - genes that are not competitors at the same locus
noun genes that are not competitors at the same locus