/ ˈædvɜːb; NAmE -vɜːrb/ noun
( grammar ) a word that adds more information about place, time, manner, cause or degree to a verb, an adjective, a phrase or another adverb :
In 'speak kindly', 'incredibly deep', 'just in time' and 'too quickly', 'kindly', 'incredibly', 'just' and 'too' are all adverbs.
—see also sentence adverb
► ad·ver·bial / ædˈvɜːbiəl; NAmE -ˈvɜːrb-/ adjective :
'Very quickly indeed' is an adverbial phrase.
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WORD ORIGIN
late Middle English : from Latin adverbium , from ad- to (expressing addition) + verbum word, verb.