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"Fallecimiento" is a noun which is often translated as "death", and "defunción" is a noun which is also often translated as "death". Learn more about the difference between "fallecimiento" and "defunción" below.
el fallecimiento()
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
la defunción()
A feminine noun is almost always used with feminine articles and adjectives (e.g., la mujer bonita, la luna llena).