Won't take long to answer: what exactly is a mode?

[PhysicsKid0123]

What exactly is a mode and what exactly is a normal mode when talking about waves and oscillations? I keep looking on the internet but I can't really find anything concrete. Some definitions are very obscure.

 

[Doug Huffman]

A normal mode of an oscillating system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation. https://en.wikipedia.org/wiki/Normal_mode

Not good enough?