It depends who will use the word. If it's one character talking or thinking about another, it's a great word, and will help to characterize both characters in one swell foop. It will also trigger many readers to react in ways that enhance what you're trying to say. Readers who understand the word will get the intent. Readers who have to look up the word will experience meretriciousness. Readers who don't know what the word means, but choose to keep reading without looking it up, will at least know that one character is using such an awfully big word to describe another, which will give them approximately the right meaning anyway.
On the other hand, if the narrator utters the word, and the narrator is not a character, that doesn't characterize the characters, it characterizes the author, and to some extent the author's relationship to the reader. It says that either you expect your readers to know what the word means, or you intend to use words whether or not the readers understand. If that's what you want, go for it.
If not, then show the character being meretricious, and the consequences of that (in the way other characters react), and let readers come to their own conclusions.