This paper showcases the development of linguistically -responsive pedagogy in a first -year writing course to facilitate students' recognition of the connection between discrete language features and purpose of definitions. Paraphrasing definitions was chosen as the first textual focus in response to disciplinary instructors' anecdotes of students talking 'around' key terms rather than being precise, and in response to their role in establishing terms within larger texts. Acknowledging the benefit of seeing language as a system, we draw on the research and (simplified) metalanguage of Systemic Functional Linguistics (Derewianka, 2011; Halliday & Matthiessen, 2004; Martin & Rose, 2005). We introduce the foundational relationship between purpose and features, then use the teaching and learning cycle (Rothery, 1994) to scaffold students' writing development through deconstruction and joint construction. Although definitions are quite specific, the process of determining their purpose, features and usage serves as a foundation for multilingual students' knowledge and skills, enabling them to respond to the varied linguistic demands of discipline-specific post-secondary writing.