According to Webster's New World College Dictionary, fidelity is the faithful devotion to duty or to one's obligations or vows. Webster's also defines fidelity as the accuracy of a description or translation, or the accuracy of the reproduction of a sound or image.

Faithfulness

Fidelity is the faithfulness to duty or responsibility. In modern usage, fidelity is a reference to the condition of a monogamous relationship or devotion to marriage vows.

Hi-Fi

High fidelity, or "Hi-Fi," is a measure of the reproduction accuracy of a source, such as a sound or image. The term was popularized in the 1950s as advances in playback technology were made. Low-fidelity reproductions typically are thought to be of a lesser quality than high-fidelity reproductions.

Wi-Fi

"Wi-Fi" is a popular abbreviation for wireless fidelity. The term, therefore, is believed to mean the reproduction accuracy of a digital source, such as a sound or image. The term Wi-Fi, however, is a commercial brand and a registered trademark owned by the Wi-Fi Alliance. The alliance is a global, not-for-profit organization formed in 1999 that supports the adoption of a single, worldwide standard for a wireless network.

Science

The fields of scientific modeling and simulation define fidelity as a measure of the realism of a model or simulation. This fidelity is in reference to the model's reproduction accuracy of a tangible or condition, which also is known as the degree of similarity.

Ethics

Fidelity is popularly thought of as a basic, ethical principle.

Source:

Webster's New World College Dictionary

Wikipedia

Wi-Fi Alliance