This paper discusses the use of grammatical terminology in English language teaching. Accepting that it is a common feature of many classrooms, the paper attempts to help teachers understand the role and nature of terminology. A distinction is made between terms which are transparent (e.g. "countable"), opaque (e.g. "verb") or iconic (e.g. "-ing form"). A number of criteria for evaluating the suitability of terminology for classroom use are also offered. In this way it is hoped that teachers will be better equipped to make well-informed decisions about the terms they choose to use in the classroom.