Following an empirical study, this article deals with a specific type of errors in vocabulary acquisition of French as a second language: intralingual lexical confusion. 480 English and Greek speaking learners (beginners, intermediates and advanced) of French were given a L2-L1 translation task of French words. A large number of errors revealed confusions due to formal and/or semantic similarity between the target words and other French words known by the learners. The formal and/or semantic comparison between error and target word allowed a narrower description of intralingual lexical confusion highlighting some precise sub-categories of what the author calls "lexical confusibles".