If you’re an artist, you might hold a “palette” in one hand while wielding your brush with the other. Your paintings could be described as representing a “palette” of colors. Then if you stop painting (and clean yourself up) you might go out to eat, hoping that something on the menu pleases your “palate.” Afterwards, being tired, not to mention being a starving artist, you might retire to your attic apartment and lie down on your “pallet.”
“Palette,” “palate,” and “pallet” are easy to mix up, probably because they sound almost exactly the same. Sometimes when that occurs it’s because the words started out as the same word and meanings diverged, but that doesn’t seem to be the case here. “Palette” comes from the Latin word “pala,” which means shovel, with “ette” added to make it a “diminutive” — that is, a smaller, petite version of the main thing. Don’t tell the artists, but their paint holders are “little shovels.”
“Palate” also comes from Latin, but this one is derived from “palatum,” meaning “roof of the mouth.” No diminutive involved. I’m pretty sure even the Romans, who had some fairly eccentric ideas from time to time, didn’t equate shovels with roofs of mouths. Normally “palate” is more associated with your sense of taste or preference than the physical structure of the mouth, but both meanings are valid. The similarity between “palette” and “palate” looks like nothing but a coincidence.
“Pallet,” which by the way is a thin bed usually filled with straw — or a wooden framework used to stack items on for shipping — also comes from Latin: “palea” means “chaff” or, basically, straw. And the “et” at the end is probably a remnant of the diminutive “ette,” so a “pallet” is a small bed that’s uncomfortably hard because it contains only a small amount of straw. And it’s straw, after all, so even adding a lot more might not help a great deal. So this word, too, isn’t really related to the others except by sounding the same.
Many times when words sound the same there’s a clever mnemonic available to keep them straight. “Principle” and “principal” can be kept straight by “your principal is a pal” — a “principal” is a person, and a “principle” isn’t. But in the case of palette, palate, and pallet, either they’re all pals or none of them are (hint: it’s none of them). The spellings otherwise are really pretty similar, and nothing really jumps out as a clue to which word goes with which meaning. The only mnemonic I can think of — and I’ve never seen this mentioned anywhere, so maybe it doesn’t really help — is that your “palate” might be satisfied if you just “ate.” As to remembering the other two, either lie back on your pallet and consider or just start painting; maybe you’ll come up with something!