polygene

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Any of a group of nonallelic genes, each having a small quantitative effect, that together produce a wide range of phenotypic variation. Also called multiple factor, quantitative gene.

Century Dictionary and Cyclopedia

1. Noting those volcanic cones which are the result of successive eruptions: contrasted with monogene. The term was suggested by A. Stübel.

Wiktionary

1. n. genetics A group of nonallelic genes that act together to produce phenotype variations

WordNet 3.0

1. n. a gene that by itself has little effect on the phenotype but which can act together with others to produce observable variations