The importance of terrain evaluation techniques in engineering geology is demonstrated by the instigation of two Engineering Group working parties on the subject that reported in 1982 and 2001. Since the second working party report ground models have emerged as one of the key requirements of ground investigations for engineering practice and this paper suggests that terrain evaluation is fundamental to the development of ground models in providing the spatial framework to facilitate interpretation. However, terrain evaluation has also emerged as the basis for creating more extensive generalized models that are required when constructing long linear structures such as roads and pipelines that cross very varied landscapes. This variation in application has led to confusion over the nomenclature used in terrain evaluation. In this paper terrain evaluation is regarded as a broad over-arching term that encompasses a range of techniques and it is suggested that its application in engineering practice should not be restricted by narrow or ambiguous definitions.