This is the 11545th most frequent Spanish word.
fantástica
Fantastic.
Here, 'fantástica' is an adjective describing a person in a highly positive manner, indicating excellent qualities or overall admiration.
María es una persona fantástica.
Maria is a fantastic person.
In this case, 'fantástica' qualifies a noun (idea) to signify that it is remarkable or splendid.
¡La idea que has tenido es fantástica!
The idea you had is fantastic!
Here, 'fantástico' (masculine form) modifies a noun (landscape) to convey a sense of beauty or amazement.