A fanciful or whimsical person.
"The fantastic old man sat by the fountain, telling stories about dragons living under the city streets."
In plain English: A fantastic is an imaginary creature from folklore or mythology, like a dragon or a unicorn.
"The fantastic was a concept I could never fully understand until I read that story."
Usage: Use "fantastic" as a noun only in rare literary contexts to describe a fanciful or whimsical person. In modern everyday speech, it functions exclusively as an adjective meaning extremely good or wonderful.
ludicrously odd
"Hamlet's assumed antic disposition"
"fantastic Halloween costumes"
"a grotesque reflection in the mirror"
extraordinarily good or great; used especially as intensifiers
"a fantastic trip to the Orient"
"the film was fantastic!"
"a howling success"
"a marvelous collection of rare books"
"had a rattling conversation about politics"
"a tremendous achievement"
existing in fancy only
"fantastic figures with bulbous heads the circumference of a bushel"
extravagantly fanciful in design, construction, appearance
"Gaudi's fantastic architecture"
Existing in or constructed from fantasy; of or relating to fantasy; fanciful.
"The architect proposed a fantastic tower that spiraled into the clouds, defying all laws of physics."
In plain English: Fantastic means something is amazing and really cool.
"The weather is fantastic today, so we decided to go for a walk in the park."
Usage: In everyday conversation, fantastic functions as an intensifier meaning excellent or wonderful rather than related to fiction. Use it to express strong approval or excitement about something real, such as saying the weather is fantastic.
The word fantastic entered English in the 16th century via Middle French and Late Latin, where it originally meant "imaginary" or "fictional." Its ultimate roots trace back to Ancient Greek, derived from a Proto-Indo-European root meaning "to shine," which gave rise to concepts of appearing real before being adopted into modern usage.