fantastisch
fantastic
As an expression of enthusiasm: very good, great, wonderful.
Das Essen in diesem Restaurant war einfach fantastisch!
The food in this restaurant was simply fantastic!

fantastic
Loading your saved state.
fantastic
As an expression of enthusiasm: very good, great, wonderful.
Das Essen in diesem Restaurant war einfach fantastisch!
The food in this restaurant was simply fantastic!

The word 'fantastisch' (fantastic/fantastical) is closely related to the noun 'die Fantasie' (fantasy/imagination). This helps you directly understand the meaning 'unreal' or 'existing only in the imagination'.
Er hat eine blühende Fantasie und erfindet fantastische Geschichten.
He has a vivid imagination and invents fantastical stories.
In the meaning 'great', 'fantastisch' (fantastic) is often used to describe personal impressions. Typical combinations are 'fantastisches Wetter' (fantastic weather), 'eine fantastische Idee' (a fantastic idea), or 'fantastisch aussehen' (to look fantastic).
Du siehst in diesem Kleid fantastisch aus!
You look fantastic in this dress!
You can recognize the meaning 'unreal' from the context. When the topic is fairy tales, myths, science fiction, or art, this meaning is usually intended. Pay attention to nouns like 'Wesen' (beings), 'Welten' (worlds), or 'Geschichten' (stories).
Der Film spielt in einer fantastischen Welt voller Magie.
The film is set in a fantastical world full of magic.
When 'fantastisch' (tremendous) describes an unbelievable size, it is often connected with numbers, money, or quantities. Typical nouns here are 'Gewinn' (profit), 'Summe' (sum), or 'Preis' (price).
Der Sportler unterschrieb einen Vertrag über eine fantastische Summe.
The athlete signed a contract for a tremendous sum.
super
'super' and 'fantastisch' both express enthusiasm and mean 'very good' in many situations. 'super' sounds very everyday and casual. People say it quickly in conversations, for example about a plan, a meal, or a piece of news. 'fantastisch' sounds a bit stronger and often a bit more special. It fits well when something is truly impressive or wonderful. In normal conversations, you can use both, but 'super' is often simpler and more neutral in everyday life, while 'fantastisch' shows more enthusiasm.

Der Blick vom Berg war einfach fantastisch.
The view from the mountain was simply fantastic.
Deine Idee für den Ausflug ist super.
Your idea for the trip is super.