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"Primero" is an adjective which is often translated as "first", and "más tarde" is a phrase which is often translated as "later". Learn more about the difference between "primero" and "más tarde" below.
primero()
An adjective is a word that describes a noun (e.g., the big dog).
1. (position)
a. first
Luis fue el primer invitado en llegar a la fiesta.Luis was the first guest to arrive at the party.
2. (in time)
3. (principal)
An adverb is a word that describes a verb, an adjective, or other adverbs (e.g., to run quickly, very tired).
This means that the noun can be masculine or feminine, depending on the gender of the noun it refers to (e.g., el doctor, la doctora).
a. the best
Era el primero en matemáticas en séptimo grado.I was the best in mathematics in seventh grade.