The article is based on a corpus of English words and technical terms obtained from contemporary texts and major up-to-date dictionaries and encyclopaedias. It gives a description of “post-” prefixation, its morphology (including derivational patterns of one-word terms and syntactic patterns of multiword terms) and semantics (including motivational ambiguity and definitions). French terms are used for comparison and contrast. Morphological and semantic properties of term-constituting lexemes are examined within the framework of an analysis of lexical productivity, which is defined by three criteria: number of existing derivatives, rules of derivation, and neological potential. The analysis also shows other aspects of derivational productivity: favourite word-class membership, semantic options, and terminologization.