This is the 2668th most frequent Spanish word.
eterna
"Eterna" means "eternal" or "everlasting."
Here, 'eterna' is used to describe the timeless and enduring quality of the friendship, implying it will last forever.
La amistad entre ellos es eterna.
The friendship between them is eternal.
In this instance, 'eterna' metaphorically conveys the continuous and unending nature of the love expressed.
Vivo en una eterna canción de amor.
I live in an eternal love song.
The use of 'eterna' denotes a perpetual and unchanging state, here applied to the season of spring as an ideal desire.