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"El invierno" is a form of "invierno", a noun which is often translated as "winter". "En" is a form of "en", a preposition which is often translated as "in". Learn more about the difference between "el invierno" and "en" below.
el invierno()
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
1. (season)
2. (rainy months) (Andes) (Central America)
Regionalism used in Central America: Guatemala, El Salvador, Honduras, Nicaragua, Costa Rica, and Panama
a. rainy season
Llegamos a Ecuador en pleno invierno.We arrived in Ecuador in the middle of the rainy season.
en()
A preposition is a word that indicates the relationship between a noun and another word (e.g., He ran through the door.).