light (v.1)youdaoicibaDictYouDict[light 词源字典]
"touch down," from Old English lihtan "to alight; alleviate, leave," from Proto-Germanic *linkhtijan, literally "to make light," from *lingkhtaz "not heavy" (see light (adj.1)). Apparently the ground sense is "to dismount a horse, etc., and thus relieve it of one's weight." To light out "leave hastily" is 1870, from a nautical meaning "move out, move heavy objects," of unknown origin but perhaps belonging to this word (compare lighter (n.1)).[light etymology, light origin, 英语词源]