As a result of the widespread use of the landslide classifications of Varnes (1978) and Hutchinson (1988), certain terms describing common types of flow like mass movements have become entrenched in the language of engineering geology. Example terms include debris flow, debris avalance and mudslide. Here more precise definitions of the terms are proposed, which would allow the terms to be retained with their original meanings while making their application less ambiguous. A new division of landslide materials is proposed, based on genetic and morphological aspects rather than arbitrary grain size limits.