How to Say "never-ending" in Spanish
The most common Spanish word for “never-ending” is “interminable” — use this word when referring to something that feels excessively long and tedious, often implying boredom.
interminable
in-tair-mee-NAH-blayinteɾmiˈnaβle

Examples
La película fue interminable y aburrida.
The movie was endless and boring.
La película fue interminable.
The movie was endless.
Tengo una lista interminable de tareas hoy.
I have a never-ending list of tasks today.
La espera en el hospital se hizo interminable.
The wait at the hospital felt like it would never end.
One Form for All
This word doesn't change based on whether the thing you are describing is masculine or feminine. You can say 'un libro interminable' or 'una película interminable'.
Emphasis through Placement
If you put this word BEFORE the noun (e.g., 'una interminable espera'), it sounds more poetic or emphasizes how annoyed or bored you are.
Gender Agreement
Mistake: “La clase fue interminabla.”
Correction: La clase fue interminable. Because it ends in 'e', it stays the same for both masculine and feminine words.
eterno
eh-TEHR-noheˈteɾno

Examples
¡Qué eternas son las clases de los lunes por la mañana!
Monday morning classes are so eternal!
La reunión se hizo eterna, duró casi tres horas.
The meeting became endless; it lasted almost three hours.
Ese eterno problema de tráfico nunca se soluciona.
That constant traffic problem is never solved.
Mi hermana es la eterna optimista, siempre ve el lado bueno.
My sister is the eternal optimist; she always sees the bright side.
Emphasis Placement
When 'eterno' is used figuratively (meaning 'constant' or 'always present'), it often goes before the noun, like in 'el eterno dilema' (the constant dilemma).
Confusing 'Constant' and 'Forever'
Mistake: “Using 'eterno' when you just mean 'frequent' or 'long'.”
Correction: Use 'largo' (long) or 'frecuente' (frequent) unless you want the strong exaggeration 'eterno'.
Interminable vs. Eterno
Related Translations
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