Semantics is a subfield of linguistics that is traditionally defined as the study of meaning of (parts of) words, phrases, sentences, and texts. Semantics can be approached from a theoretical as well as an empirical (for example psycholinguistic and neuroscientific) point of view. The decompositional perspective towards meaning holds that the meaning of words can be analyzed by defining meaning atoms or primitives, which establish a language of thought. An area of study is the meaning of compounds, another is the study of relations between different linguistic expressions (homonymy, synonymy, antonymy, polysemy, paronyms, hypernymy, hyponymy, meronymy, metonymy, holonymy, exocentric, and endocentric). Semantics includes the study of thematic roles, argument structure, and its linking to syntax. Semantics deals with sense and reference, truth conditions, and discourse analysis. Pragmatics is often considered a part of semantics, but otherwise is treated as a branch of its own.