Word: 光速 (guāngsù) 光速 dictionary entry guāngsù the speed of light; extremely quickly Full dictionary entry for 光速 Example sentences using 光速 2 sentences, showing page 1 of 1. 光速是宇宙中最快的速度。 Guāngsù shì yǔzhòu zhōng zuìkuài de sùdù. The speed of light is the fastest speed in the universe. 光速有声速的八十八万多倍。 Guāngsù yǒu shēngsù de bā shíbā wàn duō bèi. The speed of light is more than eighty-eight thousand times the speed of sound.