This lecture discusses word formation as a language subsystem and its role in enriching vocabulary. It covers the notion of neologisms, types of neologisms, types of word formation, classification of word formation, synchronic and diachronic approaches to studying word formation, productivity of word formation means, and frequency due to pragmatic relevance. Word-formation is defined as the branch of Lexicology that studies patterns and ways of creating words in a language, focusing on the derivative structure of existing words and the patterns for building new words in the English language.