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"La rosa" is a form of "rosa", a noun which is often translated as "rose". "El clavel" is a form of "clavel", a noun which is often translated as "carnation". Learn more about the difference between "la rosa" and "el clavel" below.
la rosa, el rosa()
A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
el clavel()
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).