A word is so much more than a label for its object or idea.
An actual object is unbending but when it becomes a word the possibilities of bending the perception, concept, and reality of it are endless.
Take a simple thing like licorice. To hold it in your hand it can’t be anything but licorice under a generalization of Food or Candy. However when it becomes a word it can be a scent, a texture, a visual aid ( shoes shiny as oiled licorice ), a taste, a plant, a color, and even a place - a licorice factory. The licorice doesn’t even have to be present it merely becomes concept.
Once this is realized, you can triple your vocabulary without ever having added one word. And you can include any word even an obscure one like abacus.
Now, one could dismiss it because there is no practical way for an abacus to fit in their story. But that’s when the writer is thinking of an actual abacus. Given its shape it can lead to a comparison, maybe a way to describe a room divider. I.e. She had a retro room divider resembling a giant abacus. Or a metaphor - He was figuring things out in his head. This could take a while, like a monkey with a broken abacus.
Try it out. It doesn't have to be perfect. Practice makes it better. Take a word like spittoon. You may not be writing a western but that doesn’t mean it can’t make an appearance. i.e. Rachel scowled. The man belonged to the spittoon and bar fight era when women weren’t women they were little ladies.
Go beyond first impressions of words. Turn them around and see all the angles, all the possibilities.
Take a chance.
All words have a history with people like names and scents. Say the name Rupert and most people might think of the husky-voiced actor in Harry Potter, I’m thinking of the bear in yellow check slacks. Take the word ruby - brainstorm it, to go beyond your initial history into ideas - a gem, a birthstone, Dorothy’s slippers, the color of wet blood, a pulled apart pomegranate looks like clusters of rubies. Once you can springboard from the ordinary and see all angles the word ruby ( or any word for that matter ) can make connections to things never before thought of, it ceases to remain in its rigid form. They can appear in any setting and flourish any mood. Nouns have the possibility to become verbs, and verbs to nouns, and nouns to adjectives.
When you want to add to your vocabulary, go for it.
You don’t have to join word-a-day sites ( but you can if you want ) or scour the dictionary or thesaurus to learn new words ( but again, you can if you want. ) Just keep absorbing words from a variety of sources - Non-fiction, articles, reference, guide books, ads, comics, music.
What are you looking for?
Do you want precision?
Visual & reverse dictionaries will help you discover precise names such as finial ( the decorative tip of a spire. )Or gluteus maximus (a thigh muscle) or drupelet ( the little nobs of a raspberry. )
How about ready made ideas & terms ?
Word Guides offer lists of words - such as glitter rock, bosa nova, bubblegum under the heading of Popular Music.
Need something modern or old school?
Slang books will offer current or dated doozies like - voom-voom, dollink, and cutems ( for sweetheart. )
Reference books will offer flowers you might never have thought of like boneworts, broomrape, or star-thistle.
Need something relatable?
Magazines will offer modern brandnames, and current catch phrases.
Want to be inventive? - Poetry will flip meanings and invent words - The moon makes frosty red moonburn ( this is from Al Purdy’s The Double Shadow )
Want to learn how to develop rhythm and deliver a punch? Try music - Mama, just killed a man. Put a gun against his head, pulled my trigger now he’s dead ( Bohemian Rhapsody - Freddie Mercury )
Now, how about inspiration?
Photos & Art can also fire up your vocabulary by stirring your imagination. I have no doubt that William Sleator was influenced by M.C. Escher when he wrote The House of Stairs. Even Harlan Ellison created a series of stories based off paintings by Yerka. But even a plain photo of an object or place can help you create good descriptions, as you have a reference to work with.
Learn to absorb input from your five senses. Take note of sounds, textures, tastes, scents, sights. Make movie night do double duty - note the glass like clink of bangle bracelets on actresses, and strategic stray hairs, or body language. The more you take time to note these things - the more seamlessly your character will notice them. Practice will reward you with cleaner observations, better flow and the right word.
Whether or not you add words to your vocabulary isn’t as important as developing an appreciation for words and learning how to use what’s already ingrained. It’s about developing your own eye and seeing something in a word that no one else does.