This article offers a review of the causes of denominative variation in terminology observed by different authors, based on a classification of the areas that motivate variation and illustrated by examples of the most relevant types of variation in the present context. This analysis offers a typology of the causes and sub-causes of denominative variation in terminology. It is presented in five main sections: dialectal causes, related to different origins of authors; functional causes, related to different communicative registers; discursive causes, related to different stylistic and expressive needs of authors; interlinguistic causes, related to contact between languages; and cognitive causes, related to different conceptualisations and motivations.