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"Nochebuena" is a form of "nochebuena", a noun which is often translated as "poinsettia". "Navidad" is a proper noun which is often translated as "Christmas". Learn more about the difference between "nochebuena" and "Navidad" below.
la nochebuena()
A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
a. poinsettia
Adornamos la casa por dentro y por fuera con nochebuenas en la temporada navideña.We decorate the house inside and out with poinsettias during the Christmas season.
la Navidad()
A proper noun refers to the name of a person, place, or thing.
las Navidades
A plural noun indicates that there is more than one person, place, thing, or idea.
a. Christmas
Vamos a pasar las Navidades con mis suegros.We're going to spend Christmas with my in-laws.