Here are 20 cool vocabulary words that may be useful for those looking to elevate their language skills:

Ennui (n.) – A feeling of listlessness and boredom; a lack of interest or excitement.
Perspicacious (adj.) – Having a keen understanding and insight; able to notice and understand things that are not immediately apparent.
Fastidious (adj.) – Meticulous and demanding in one’s standards; having a strong attention to detail.
Ephemeral (adj.) – Lasting for a very short time; transitory.
Cacophony (n.) – A harsh, discordant sound; a mixture of loud, unpleasant noises.
Meritorious (adj.) – Deserving praise or reward; having merit or value.
Sagacious (adj.) – Having keen discernment and good judgment; wise and perceptive.
Nebulous (adj.) – Unclear or vague in meaning or form; lacking definition or distinctness.
Perfidious (adj.) – Disloyal or treacherous; having a tendency to betray trust.
Dissatisfaction (n.) – A feeling of discontent or unhappiness with something.
Enthrall (v.) – To captivate or fascinate someone; to beguile or entertain.
Rigor (n.) – A state of being firm and unyielding in one’s principles or standards.
Abstruse (adj.) – Difficult to understand; obscure or complicated.
Lassitude (n.) – A feeling of weariness or exhaustion; a lack of energy or enthusiasm.
Eloquent (adj.) – Given to using language in a skillful and persuasive way.

And here are some more advanced words:

Thixotropy (n.) – The property of a fluid that becomes less viscous when agitated and more viscous when left still.
Chiaroscurist (n.) – An artist who specializes in the use of chiaroscuro, an artistic technique that uses strong contrasts between light and dark to create a sense of volume and depth.
Sesquipedalian (adj.) – Given to using long words; given to being verbose or flowery in one’s language.
Crepuscular (adj.) – Relating to or resembling twilight; having a soft, yellowish light.
Fastidious (adj.) – Meticulous and demanding in one’s standards; having a strong attention to detail.

I hope these words are helpful!