prefix
prefix (prefijo)
a word part added to the beginning of a word that changes its meaning.
Example
The answer was unclear, so she reread the memo. (Un- means not; re- means again.)
In Spanish
prefix (prefijo) — una parte de palabra que se añade al comienzo de una palabra y cambia su significado.
The answer was unclear, so she reread the memo. (Un- significa no; re- significa otra vez.)