Prefixes are lexical units that are written at the beginning of a word to form a new one with a different meaning. According to the meaning they provide, they are classified into spatial, temporal, aspectual, quantifying, reflective, reciprocal, associative, gradative, negative and orientation prefixes. For example: antebrazo - forearm (spatial); bilingüe - bilingual (quantifying); infravalorar - undervalue (grade))