Audio and electronics
In audio, "fidelity" denotes how accurately a copy reproduces its source. For example, a worn gramophone record will have a lower fidelity than one in good condition, and a recording made by a low budget record company in the early 20th century is likely to have significantly less audio fidelity than a good modern recording. In the 1950s, the terms "high fidelity" or "hi-fi" were popularized for equipment and recordings which exhibited more accurate sound reproduction. Similarly in electronics, fidelity refers to the correspondence of the output signal to the input signal, rather than sound quality, as in the popular internet connection technology "Wi-Fi".
The term "lo-fi" has existed since at least the 1950s, shortly after the acceptance of "hi-fi", but its definition evolved continuously between the 1970s and 2000s. In the 1976 edition of the Oxford Dictionary, lo-fi was added under the definition of "sound production less good in quality than 'hi-fi,'" and in the glossary of the 1977 book The Tuning of the World, was defined as "unfavourable signal-to-noise ratio." By the end of the 1980s, rock music critics were attributing qualities such as "home-recorded", "technically primitive", and "inexpensive equipment" to the "lo-fi" label, and throughout the 1990s, such ideas became central to how the descriptor was popularly understood. Consequently, in 2003, the Oxford Dictionary added a second definition for the term—"a genre of rock music characterized by minimal production, giving a raw and unsophisticated sound". A third was added in 2008: "unpolished, amateurish, or technologically unsophisticated, esp. as a deliberate aesthetic choice."