Rosa vs. cor-de-rosa
In Portuguese, the color pink can be expressed as rosa or cor-de-rosa. While they refer to the exact same hue, the main difference lies in their grammatical behavior. Rosa is concise and flexible, while cor-de-rosa is a compound descriptive term that follows a strict rule of never changing its form.
Rosa
A1This word refers to both the flower (the rose) and the color. It is the most common, short way to say pink. grammatically, when used as an adjective, strictly speaking it should be invariable, but in common usage, it is often pluralized to rosas to match plural nouns.
Eu comprei uma camisa rosa para a festa.
(I bought a pink shirt for the party.)
Os cadernos das crianças são rosas.
(The children's notebooks are pink.)
O céu ficou rosa durante o pôr do sol.
(The sky turned pink during the sunset.)
Ela adora batom rosa.
(She loves pink lipstick.)
Cor-de-rosa
A1This is a compound word literally translating to color-of-rose. It is used exclusively as an adjective to describe objects. The most distinct feature of cor-de-rosa is that it is invariable; it never changes for gender (masculine/feminine) or number (singular/plural), even when describing plural objects.
Elas compraram sapatos cor-de-rosa.
(They bought pink shoes.)
A pantera cor-de-rosa é um personagem famoso.
(The pink panther is a famous character.)
Nós vimos várias casas cor-de-rosa na rua.
(We saw several pink houses on the street.)
Ele me deu um laço cor-de-rosa.
(He gave me a pink ribbon.)
Summary
Both words mean pink. Choose rosa for brevity and everyday speech, noting that many speakers pluralize it (e.g., flores rosas). Choose cor-de-rosa for a more descriptive tone and remember that it strictly remains singular and gender-neutral in all contexts (e.g., flores cor-de-rosa).