Adecuado vs. idóneo vs. apropiado
The Spanish words 'adecuado', 'idóneo', and 'apropiado' translate to 'suitable', 'appropriate' in English, but each word can be used in a slightly different context. 'Adecuado' refers to something fitting or convenient; 'idóneo' implies suitability based on aptitude or qualification; 'apropiado' emphasizes relevance or appropriates to a specific situation.
Adecuado
'Adecuado' is the equivalent of 'suitable' or 'adequate'. It means fitting, convenient, or having the quality of adapting to the circumstances or purpose.
Es la hora adecuada para salir a caminar.
(It's the right time to go for a walk.)
Esto no es adecuado para niños.
(This is not suitable for children.)
Idóneo
'Idóneo' refers to something being apt, qualified or most suitable due to qualifications or abilities. It relates more towards proficiency and capability.
Es el candidato idóneo para el trabajo gracias a su experiencia y habilidades.
(He is the ideal candidate for the job thanks to his experience and skills.)
Hoy es un día idóneo para visitar el parque.
(Today is a perfect day to visit the park.)
Apropiado
'Apropiado' implies something that is appropriate, correct or suitable under particular circumstances. It is largely associated with relevance and propriety.
No es apropiado vestirse así para una boda.
(It's not appropriate to dress like that for a wedding.)
Este libro es apropiado para tu nivel de lectura.
(This book is appropriate for your reading level.)
Summary
'Adecuado', 'idóneo', and 'apropiado' all refer to something being suitable or appropriate, but they emphasise different facets. Where 'adecuado' is about fittingness and convenience under specific circumstances, 'idóneo' implies suitability due to proficiency and capabilities, while 'apropiado' signifies relevance and propriety. Depending on what quality one wishes to emphasize—convenience, capability, or propriety—one would choose among these words.