Answer: Polygenic means that most traits are controlled by an additive effect of two or more genes on a single phenotype.
Explanation: Polygenic inheritance or quantitative characters are those that vary in the population along a continuum. For example, height, skin color, etc.
Often, penetrance, pleiotropy, epistasis, expressivity and environmental factors are involved in producing a continuous distribution of phenotypes.
Traits such as height that show a continuous range of variation and do not behave in a single Mendelian fashion are known as quantitative or complex traits.