adverb, adverbial: a word that modifies a verb or verbal phrase. An adverbial phrase or clause similarly functions as a verbal modifier. E.g. in she spoke quickly, the word "quickly" is an adverb which modifies the verb "spoke". Modifiers of adjectives, adpositional structures, and adverbs are also considered adverbial. For example, in the adverbial phrase "very quickly", "very" modifies the adverb quickly, and is therefore considered to be an adverb. [Spanish: adverbio, adverbial]