But choosing the right dictionary isn't as simple as grabbing the first one you see, the fattest one or the one with the most familiar title. Affect is almost exclusively a verb. Existing or being everywhere at the same time, constantly encountered, widespread. A sudden perception of the essential nature or meaning of something, an illuminating discovery, an often striking intuitive grasp of reality. That name doesn't make it good.
Quality depends more on a reputable publishing house.
Merriam-Webster, for instance, is the only one with a direct link to Noah Webster, the famed American lexicographer. Children don't have the ability to use a huge, unabridged dictionary, or even the most common college-level book. But that doesn't mean they're too young to look up words. A dictionary is a valuable tool for teaching them how to find information instead of waiting for it to pop up on a computer screen. The expected use level for most dictionaries is clearly indicated, from young readers to middle or high school to college and beyond.