Translators often face the challenge of choosing among a plethora of terminological variants which have a similar meaning. Denominative variation, also known as terminological variation, causes uncertainty in the mind of the translator not only when looking for translation equivalents but also from a cognitive point of view. Uncertainty is also an issue when the translator is not sure whether the target audience will be familiar with the terminological variant s/he has chosen. Uncertainty is a real challenge for translators and researchers alike requiring the creation of terminological databases adapted to the needs of translators. VariMed is a terminological resource which focuses on the cognitive and communicative motivations of denominative variation, and their reflection in the terminological variants of a concept. The aim of this paper is to explore the grey areas related to the translation of denominative variation in medical translation, a phenomenon taking place both at the intralinguistic and interlinguistic level within the framework of the research projects VariMed et CombiMed. We also study the cognitive phenomenon of familiarity (Delgado 1988; Connine, Mullennix et al. 1990; Gómez Veiga, Carriedo López et al. 2010) among non-experts as an additional source of doubt on the part of the translator. To this end, we experimentally studied which terminological variants trainee translators perceived as more familiar in spontaneous production tasks based on data from the VariMed database. The results of the experiment shed some light on the parameters that influence familiarity with words and terms, and thus, the lexical choices of translators.