The dissertation seeks to explore the linguistic features and regularities of functional transposition in the English language of the 9th–21st centuries. Transpositional processes are traditionally reviewed as one of the word formation processes, aimed at a new lexeme formation by means of morphological, syntactic and semantic changes of an original unit. Such perspective equates transposition with other types of word formation, for instance, transfer, conversion, zero derivation, transition, transcategoriality etc. and confines it to open word classes. Referring to the units of closed word classes, none of the elements in the ‘form-function-meaning’ triad provides a solid and unanimous answer to the question of overlapping. Since morphologically and semantically identical units function as representatives of several parts of speech, we consider it plausible to speak of their functional transposition from one part of speech into another. Therefore, functional transposition is interpreted as cognitively and communicatively preconditioned diachronic and synchronic process and its result, which presupposes the ability of lexical-grammatical units by means of grammaticalization and lexicalization without the use of morphological and/or syntactical markers to instrument functions inherent to the transposed part of speech and remain within the own initial part of speech. Such exposition of the transpositional processes and failure of the ‘form-function-meaning’ triad to explain them determine the urge to develop the etymological functionalism approach which is aimed at exploring the development of initial and transposed categories and is the cornerstone of functional transposition.
Overlapping of prepositions, adverbs, and conjunctions can be tracked by means of their diachronic study, which is based on the analysis of 402 prescriptive and descriptive grammar books of the 18th–21st centuries with reference to the classical grammatical theories, which form the cornerstone of the part of speech theory. The analysis results into the unique paradigm of parts of speech classifications of the 18th–21st century grammar, which comprises over 30 independent approaches.
Contrary to prepositions, adverbs are characterized by wide transpositional potential, what is attested by 50% of adverbs, viz. ‘aboard’, ‘across’, ‘alongside’, ‘astride’, ‘behind’, ‘inside’, ‘opposite’, ‘since’, and ‘within’, as the frequency of the transposed categories surpasses the frequency of the initial categories. The other adverbs, viz. along’, ‘around’, ‘below’, ‘down’, ‘off’, ‘out’, ‘outside’, ‘round’, and ‘up’, have to some extent been grammaticalized and have preserved the tendency to grammaticalization and further successful functional transposition. The adverbs ‘down’, ‘out’, and ‘up’ are the exceptions, as their level of development has not been lower than 90%. It means that these adverbs are primitive lexical units, which lie in the foundation of speakers’ cognitive and communicative models and are not interpreted as other parts of speech.
The category of conjunctions is deprived of transpositional potential, as its units viz. ‘till’, ‘until’, and ‘since’ have transposed from the categories of prepositions and adverbs. Substantial potential to be transposed into conjunctions is represented by the prepositions ‘after’ and ‘before’. Transposition into conjunctions is based on the seme of temporality, what is unusual for transpositional processes between prepositions and adverbs, as they are predominantly determined by the seme of locativity.
Despite current overlapping, ‘near’ and ‘underneath’ have been developing independently on the basis of the adjective ‘near’ and the preposition and adverb ‘under’.
