How to Say "complement" in Spanish
The most common Spanish word for “complement” is “complemento” — use 'complemento' for an item that adds to or completes another, often in a fashion or decorative sense, or for a general notion of something that completes..
complemento
/kom-ple-MEN-toh//kompleˈmento/

Examples
El sombrero es un bonito complemento para su atuendo.
The hat is a nice accessory for her outfit.
Llevo un collar rojo como complemento.
I'm wearing a red necklace as an accessory.
Este bolso es el complemento ideal para tu vestido.
This bag is the perfect accessory for your dress.
Recibió un complemento salarial este mes.
He received a salary supplement this month.
One word, many 'additions'
In English, we use different words for a 'necklace' (accessory), 'extra pay' (bonus), and a 'direct object' (grammar). In Spanish, 'complemento' covers all these 'extra pieces' that finish or complete something else.
Grammar without the jargon
In school, you'll hear 'complemento directo.' This simply refers to the thing or person that receives the action in a sentence, like 'the book' in 'I read the book.'
Don't just say 'Accesorio'
Mistake: “Only using 'accesorio' for fashion.”
Correction: Use 'complemento' frequently! While 'accesorio' is correct, Spanish speakers often prefer 'complemento' when talking about things that 'complete' an outfit.
complementario
/kom-ple-men-ta-ryo//komplemenˈtaɾjo/

Examples
El complemento de A es el conjunto de todos los elementos que no están en A.
The complement of A is the set of all elements not in A.
Calcula el complementario del conjunto A.
Calculate the complement of set A.
Using it as a Noun
When used as a noun, it usually refers to a specific concept in math (like sets) or grammar. It is almost always masculine ('el complementario').
Choosing between 'complemento' and 'complementario'
Related Translations
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