Logos (UK: /ˈloʊɡɒs, ˈlɒɡɒs/, US: /ˈloʊɡoʊs/; Ancient Greek: λόγος, romanized: lógos, lit. 'word, discourse, or reason') is a term used in Western philosophy, psychology and rhetoric, as well as religion (notably Christianity); among its connotations is that of a rational form of discourse that relies on inductive and deductive reasoning.
Aristotle first systematized the usage of the word, making it one of the three principles of rhetoric alongside ethos and pathos. This original use identifies the word closely to the structure and content of language or text. Both Plato and Aristotle used the term logos (along with rhema) to refer to sentences and propositions.