A trait that can possibly mask another trait is known as

The answer would be dominant trait.

There are two types of traits; dominant and recessive. A dominant trait is always expressed in an organism. Meaning the trait that it carries will physically manifest in an organism.

A recessive trait in an organism is only expressed if two copies of it are present. If a dominant trait is paired with a recessive trait it will mask the recessive trait. In other words, the dominant trait will be expressed despite the recessive trait being present.