second
131Second harmonic generation — (SHG; also called frequency doubling) is a nonlinear optical process, in which photons interacting with a nonlinear material are effectively combined to form new photons with twice the energy, and therefore twice the frequency and half the… …
132Second wind — is a phenomenon in distance running, such as marathons or road running (as well as other sports), whereby an athlete who is too out of breath and tired to continue suddenly finds the strength to press on at top performance with less exertion. The …
