This is the 3868th most frequent Spanish word.
tercio
"Tercio" means "third" or "one-third" in English.
Here, "tercio" is used to indicate a fraction or proportion of a whole, specifically one-third.
Un tercio de los estudiantes llegaron tarde.
A third of the students arrived late.
"Tercio" in this context refers to a historical term meaning a type of Spanish armed formation.
En la Edad Media, un tercio era una unidad militar española.
In the Middle Ages, a tercio was a Spanish military unit.
In this sentence, "tercio" is part of the phrase "cambiar el tercio," meaning to change the subject or direction of the conversation.