Grief, an emotional response to loss

Attenuation, a reduction in amplitude and intensity of a signal

Path loss, the attenuation undergone by an electromagnetic wave in transit from a transmitter to a receiver

Animal loss, grief over the loss of an animal

Lord Loss (character), the Demon Lord from Darren Shan's 10 book series The Demonata

Free-space path loss, the loss in signal strength that would result if all influences were sufficiently removed having no effect on its propagation

Return loss, the ratio of the amplitude of the reflected wave to the amplitude of the incident wave

Insertion loss, the decrease in transmitted signal power resulting from the insertion of a device in a transmission line or optical fiber

"The Loss" (TNG episode), a fourth-season episode of Star Trek: The Next Generation

Joe Loss, the founder of The Joe Loss Orchestra

Loss (baseball), a pitching statistic in baseball

Coupling loss, the loss that occurs when energy is transferred from one circuit, optical device, or medium to another

Reflection loss, a loss which causes energy to be reflected back toward its source

Loss (film), a 2008 film by Maris Martinsons.

Loss (album), the debut album of Mull Historical Society

Bridging loss, the loss that results when an impedance is connected across a transmission line

Angular misalignment loss, power loss caused by the deviation from optimum angular alignment

Stop loss

Loss (comics), a mutant comic book character

A negative difference between retail price and cost of production