The paper deals with enantiosemy also called contronymy, auto-antonomy, and antagonymy, which has not found much attention of scholars. Enantiosemy is a case of polysemy where one meaning is in some respect the opposite of another. The paper studies the problem of enantiosemy in English legal vocabulary, which in itself presupposes definiteness and unambiguity, and focuses on the terms which contain opposite meanings within a single word form (e.g. TENANT a:, one who has the occupation or temporary possession of lands or tenements of another.; b:, one who holds or possesses real estate or personal property.). Although this linguistic phenomenon is to a certain extent marginal, it poses serious difficulties in understanding and translation. The paper is aimed at the analysis of enantiosemic legal terms with the focus on translation and second language teaching (SLT). The data were taken from dictionaries, legal texts, newspapers as well as British National Corpora (BNC), Corpus of Contemporary American English (COCA) and other Internet resources. Drawing on equivalence theory, descriptive theory, distributive theory and discourse analysis the study explores the semantic and functional features of enantiosemic terms and the role of context in defining their meaning. The results obtained testify to the existence of terminological enantiosemy and challenge the opinion that terms are monosemantic and independent of the context. The paper suggests some practical recommendations for the translation of enantiosemic legal terms in second language teaching. The findings can be used in lexicography to specify some dictionary entries, they can also find application in the theory and practice of translation and in teaching Professional English to Law students.