How to Say "ineffective" in Spanish
The Spanish word for “ineffective” is “inútil” — B1 level. This is a very common word in everyday Spanish.

Examples
La contraseña era tan larga que la memorización resultó inútil.
The password was so long that memorizing it turned out to be useless.
Esta herramienta está rota; es completamente inútil para el trabajo.
This tool is broken; it is completely useless for the job.
Fue un intento inútil de convencerla, ya tenía su decisión tomada.
It was a useless attempt to convince her; she had already made up her mind.
Adjective Form Stays the Same
Unlike most Spanish adjectives, 'inútil' uses the exact same form whether it is describing a masculine thing (el libro inútil) or a feminine thing (la llave inútil).
Forming the Plural
To make it plural, you simply add '-es': 'inútiles' (los objetos inútiles, las ideas inútiles).
Incorrect Gender Agreement
Mistake: “La herramienta inútila.”
Correction: La herramienta inútil. (Remember, it doesn't change based on gender, only on number.)
Related Translations
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