Terms are the words used for different technical and scientific notions. They form a microsystem of the language that is characterized by antonymy, synonymy, polysemy. It is considered that a term should have, in a certain area of specialty, a single referent, not more; thus, there are polysemantic terms, used in different meanings in distinct fields of knowledge. Usually, they are recorded in the explanatory dictionaries with the indication in parentheses of the sphere, the science in which they are used. However, there are situations where we deduce from the lexicographic definition that a lexical unit is a term, since the syntagmatic mention is missing.