Wiktionary
n. (context philosophy English) The shift which occurred in philosophical attention, during the 20th century and within a number of philosophical school of thought, from traditional themes of metaphysics and epistemology to a focus on the structure and usage of language and the relation of language to human understanding of those traditional themes.
Wikipedia
The linguistic turn was a major development in Western philosophy during the early 20th century, the most important characteristic of which is the focusing of philosophy and the other humanities primarily on the relationship between philosophy and language.
Very different intellectual movements were associated with the "linguistic turn", although the term itself is commonly thought to be popularised by Richard Rorty's 1967 anthology The Linguistic Turn, in which it is taken to mean the turn towards linguistic philosophy. According to Rorty, who later dissociated himself from linguistic philosophy and analytic philosophy generally, the phrase "the linguistic turn" originated with philosopher Gustav Bergmann.