Adverb - হলো এমন word যা বাক্যে noun বা Pronoun ছাড়া যে কোনো Part of Speech -কে অথবা একটি গোটা বাক্যকে modify বা বিশেষিত করতে পারে। -Dipak runs quickly. [quickly modifies runs, a verb] - Lila is a very beautiful girl . [very modifies beautiful, an adjective ] - She sings extremely well. [extremely modifies well, an adverb.] - Unfortunately, he could not continue his studies. [Unfortunately modifies a whole sentence]
[Source: Applied English Grammar and Composition, P C DAS]