The concept of reduction is discussed in most phonetics courses and is frequently used in modern linguistic research. Despite its common usage, it is understood in various ways depending on the research field and tradition. Contrary to popular belief, this term is not only applied to vowels. This article briefly examines its history from the 18th to the 20th centuries. Drawing primarily on Russian and English sources, an attempt is made to establish the period in which reduction consistently entered linguistic usage and received its first definitions (18th–19th centuries). Special attention is paid to Eduard Sievers’ “Foundations of Phonetics”, where a detailed description of reduction was first provided. Subsequently, the article describes the process of integrating this concept into the Russian philological tradition: substitute terms used in linguistic works until the end of the 19th century are examined, and the period in which reduction became established in Russian usage is determined. In particular, it is established that Sievers’ “Foundations...” played a significant role in Russian researchers’ perception of reduction. Finally, the paper briefly outlines the use of the concept in the 20th century; particular attention is paid to the shift of focus to vowel processes under the influence of the works of L. V. Shcherba and (later) Björn Lindblom. It is noteworthy that Shcherba’s observations on vowels largely anticipated Lindblom’s concept, yet this fact has scarcely received due attention in the phonetic literature.