Objective measurement in translation evaluation is a relatively untouched area, especially at the level of the lexis. No thoroughly worked-out method has been put forward for the scientific evaluation of a translation. Yet few translators would question the potential value of such a device. Certainly translation evaluation is not limited to the lexis, but it is the vocabulary items which form the building blocks that make up the whole text. So perhaps this is the best level for translation evaluation to start at, that is lexical translation evaluation. The article focuses on how the determination of the relative degree of core-ness of a given vocabulary item (i.e. the degree to which it belongs to the core vocabulary of the language) can help one find the best equivalent in another language (hence COLTE). Adopting a quantitative approach, we attempt to devise a scalar test of lexical equivalence.