The question is not vague. There is an official definition of power signal in electronics. Most who have studied signals will come across it, but it is often forgotten as an unimportant definition.
It's a signal with non-zero but finite average signal power. It is often contrasted with energy signals, which are signals with finite signal energy.
Power signals have non-zero average power and zero energy.
Energy signals have non-zero energy and zero average power.
For example, a sinusoidal signal is a power signal, while a signal pulse is an energy signal.