yellowish
Slightly yellow in color, but not fully bright yellow.
Yellowish means having a slight yellow color or tint, like something that's not quite fully yellow but shows hints of it. A piece of paper that's been sitting in the sun for years might turn yellowish instead of staying bright white. Old photographs often look yellowish because the chemicals in them change over time.
When you describe something as yellowish, you're saying it has some yellow in it but mixed with another color, usually white, brown, or gray. A banana that's starting to ripen might look greenish-yellow before turning completely yellow. Some types of cheese are yellowish rather than pure white or bright yellow.
If you can't decide whether something is yellow or cream or beige, calling it yellowish gives you a way to describe what you see without having to be too precise. It's the difference between pointing at a color and saying “that's yellow!” versus “well, it's sort of yellowish.”