Recently, I've received several queries that "helpfully" define words for me.
This is a bad tactic.
Don't employ it.
If you use a word I don't understand, I'll look it up. I like meeting new words. I particularly like meeting new words that light up a sentence.
Two recent examples:
Lexan: bulletproof glass
bycatch: what's caught in a fishing net that's not being fished for
Some of my clients are so deft with words that even when I think they've made a mistake, I look it up before slashing with my red pen (Steve Ulfelder does this in every single manuscript.)
And I love made up words too. If I look a word up, and it's not there, I go back to the sentence to see if I can make sense of it from context.
Telling me what a word means (particularly a plain old ordinary word that's already in my word hoard) does two things:
1. it annoys me because it insults my intelligence. You think I don't know that word? Here let me bop you on the head with my annotated edition of Ulysses.
2. it takes up valuable real estate in your query letter. You have 250 words max. You spend 10 of them telling me something obvious, and you're wasting resources.
Other things that waste query space:
1. Telling me your title is a "working title" and listing other choices. I don't care. Call it anything up to and including "My next bestseller" and if it sounds enticing, I'll read it.
2. Telling me your elaborate plans to promote the novel. I assume anyone will be willing to promote their book, but we'll have that conversation at a later date.
3. Telling me your critique group/beta readers/paid editor love the book. That's all well and good, but I don't care. My opinion is the only one that matters. If I don't like it, God Herself could have a different opinion and I still wouldn't take it on.
A good query is very simple. That means it's Very Hard to Write. Part of getting to simple is learning what to leave out. Definitions are on the list. Know what I mean?