Grammatical category (part of speech) that serves to modify verbs, adjectives, other adverbs, and whole clauses semantically. Adverbs cannot be declined (declension) and thus are often grouped with prepositions and conjunctions as a subgroup of particles. Adverbs form a very heterogeneous group, containing numerous overlappings with other parts of speech, which is why they can be classified grammatically in a variety of ways.
The following divisions can be made according to the particular classification of an adverb. (a) Syntactically, a distinction is made between adverbs which occur freely (evenings, downhill, gladly) and so-called ‘pronominal adverbs’ (whereof, wherein, hereby), which appear as pro-forms of prepositional phrases or adverbials. With regard to use, a distinction is usually drawn between adverbs which can be used both adverbially and attributively (The book is here vs this book here) and those which can be used only adverbially (They work quickly). Sentence adverbs (such as hopefully, maybe, probably) form a special class which can be used adsententially (sentence adverbial), that is, which constitute speaker judgments about the whole statement. (b) Semantically, there are groups with temporal (now, afterwards, yesterday), spatial (here, inside, there), modal (gladly, reluctantly), and causal (correspondingly, regardless, notwithstanding) meaning, or which show degree (very, somewhat). (c) Morphologically, adverbs can be classified as pure adverbs (soon, now), compound adverbs (forthwith, henceforth), and derived adverbs (skyward, completely).
