This paper investigates the question of compounding as a productive word-formation process in Scientific English by exploring the concepts of collocation and lexicalisation. The claim is that compounds can exhibit different internal structures, including syntactically ambiguous forms, as is the case with the noun + prepositional phrase. Frequency of co-occurrence and the unique meaning of all elements, together with the phenomenon of technicalisation, argue in favour of such an assumption. Some constraints, however, must be admitted. On occasions, the semantic type of the head noun (abstract, concrete, proper, common) can determine whether a particular construction is to be classified as a compound or not. Adapted from the source document