Because the suffix originates as a reinterpretation of the Latin feminine noun formmente inablatival locutions [such asclārāmente(literally“with a clear mind”), whenceItalianchiaramente]; if the root adjective ends in-o, in formation of the adverb it is employed in its feminine singular form.
-mente is generally added to the feminine form of the adjective, as that is the grammatical gender ofmente(“mind”). e.g.fisicamente, formed withfísica rather thanfísico. However, if the adjective ends with-ês, using the masculine form is the traditional and standard practice, as those adjectives wereepicene until the beginning of the 16th century.
In sequences of adverbs formed with-mente, it is traditionally dropped from all adverbs except the last in the sequence:
Adverbs in-mente are formed from the feminine singular forms of adjectives. For example,nuevamente(“newly”) is formed fromnueva(“new”), andcomúnmente(“commonly”) is formed fromcomún(“common”).
Not all words ending in-mente are adverbs formed with this suffix. For example,vehemente anddemente are both adjectives. In fact, adverbsvehementemente anddementemente both exist.
If the adjective is written with an accent, then the adverb with-mente is written with an accent in the same place; hencecomúnmente,rápidamente, and so on. Conversely, if the adjective is written without an accent, then the adverb with-mente is also written without an accent; hencelentamente,nuevamente, and so on.
In a string of adverbs connected with a conjunction,-mente may be omitted from all but the last: "vaga,rápidaydescuidadamente"
