The special vocabulary and cognitive syntax of a concrete language for special purposes (= technolect) differ from those of general-purpose standard language in a number of respects. The latter has functions that are alien from languages for special purposes. The primary function of technolects is their instrumental function. In addition, they are characterised by cognitive and communicative functions. However, functions that lie at the heart of natural language, such as the expressive, impressive, and poetic functions, do not belong to the set of functions of technolects. Special vocabularies are characterised by the principles of (1) adequacy, (2) actuality, and (3) productivity. The degree of adequacy is determined by the quantity of special knowledge involved, whereas that of actuality is determined by its quality. Productivity means the potential predicted for the given special branch of knowledge. On the semantic plane, technolects are characterised by monosemy; on the morphological plane, by simplification, and on the stylistic plane, by neutrality. In addition, they are typically characterised by (1) the openness of the terminological stock; (2) orientation towards classical languages in coining new terms; and (3) susceptibility to conceptual refashioning of terms due to various interdisciplinary connections. Additional functions that can be attributed to special texts are those of (1) accumulation, (2) transmission, and (3) knowledge improvement. Successful application of the first of these means, among other things, the necessity to reconstruct the appropriate theoretical context that the given quantity of knowledge fits into. The function of transmission requires an actualisation of the specialised information to the given receiver. The function of knowledge improvement, in turn, stems from the nature of technical communication whose basic task is a quest for ever newer forms of knowledge. The semantic coherence of specialised texts is expressed in phenomena like (1) thematic progression, (2) synsemanticity of the individual sentences, (3) multiple repetitions of the same terms, as well as (4) anaphora and cataphora.