Unfamiliar Words with Meanings and Part of Speech:
Word: Ephemeral
Meaning: Lasting for a very short time; fleeting
Part of Speech: Adjective
Word: Flibbertigibbet
Meaning: A frivolous, flighty, or eccentric person
Part of Speech: Noun
Word: Petrichor
Meaning: The pleasant, earthy smell after rain
Part of Speech: Noun
Word: Serendipity
Meaning: The occurrence and development of events by chance in a happy or beneficial way
Part of Speech: Noun
Word: Mellifluous
Meaning: Sweet or musical; pleasing to the ear
Part of Speech: Adjective
Word: Ubiquitous
Meaning: Present, appearing, or found everywhere
Part of Speech: Adjective
Word: Quixotic
Meaning: Exceedingly idealistic; unrealistic and impractical
Part of Speech: Adjective
Word: Obstreperous
Meaning: Noisy and difficult to control
Part of Speech: Adjective
Word: Halcyon
Meaning: Denoting a period of time in the past that was idyllically happy and peaceful
Part of Speech: Adjective
Word: Cacography
Meaning: Bad or incorrect spelling
Part of Speech: Noun
Word: Sesquipedalian
Meaning: Using long words
Part of Speech: Adjective
Word: Schadenfreude
Meaning: Pleasure derived from the misfortunes of others
Part of Speech: Noun
Word: Ephemeris
Meaning: A table showing the daily positions of celestial objects
Part of Speech: Noun
Word: Soporific
Meaning: Tending to induce drowsiness or sleep
Part of Speech: Adjective
Word: Scintillating
Meaning: Sparkling or shining brightly
Part of Speech: Adjective
Word: Loquacious
Meaning: Tending to talk a great deal; talkative
Part of Speech: Adjective
Word: Lugubrious
Meaning: Mournful, dismal, or gloomy
Part of Speech: Adjective
This is just a small sample, and there are many other unfamiliar words out there!