Decoration (noun). specifically, any mark of honor to be worn upon the person, as a medal, cross, or ribbon of an order of knighthood, bestowed for services in war, great achievements in literature, art, etc. Origin: [LL. decoratio: cf.
A P-N junction (or N-P junction) is formed by creating two substrate materials of P type and N type on a semiconductor. P type means it is doped with free holes (electron depletion) and the N type is doped with electrons. Of course by physics, the free holes and free electrons would like to neutralize each other.
P-Waves (P stands for primary or pressure or push-pull). These waves are also called longitudinal waves or compressional waves due to particle compression during their transport. These waves involve compression and rarefaction of the material as the wave passes through is but not rotation.