A style of storytelling in which plot does not unfold chronologically (e.g. Go, Pulp Fiction, Rashomon). One or two flashbacks does not make a film non-linear, but an extended flashback might (e.g. Crouching Tiger, Hidden Dragon).
Refers to a device or process in which the output is not directly proportional to the input. Often used in the satellite communication context to refer to the (undesirable) characteristics of practical high power amplifiers.
Anything other than linear. A non-linear relationship between the input and output of an amplifier, loudspeaker, or whatever creates harmonic and intermodulation distortion.
Systems that behave in an unexpected way, not changing proportionally to a change in input. Sometimes going down when you expect them to go up, doing nothing instead, or changing drastically with only minor changes to the input. Nonlinear systems fail the mathematical principle of 'superposition'.