*leuk-
原始印欧语根,意为“光,亮度”。
它构成了以下词语的全部或部分: allumette; elucidate; illumination; illustration; lea; leukemia; leuko-; light(n.)“亮度,辐射能量”; lightning; limn; link(n.2)“沥青,麻花等的火炬”; lucent; lucid; Lucifer; luciferase; luciferous; lucifugous; lucubrate; lucubration; luculent; lumen; Luminal; luminary; luminate; luminescence; luminous; luna; lunacy; lunar; Lunarian; lunate; lunation; lunatic; lune; lunette; luni-; luster; lustrum; lux; pellucid; sublunary; translucent。
它是假设的源头,其存在的证据由以下语言提供:梵语 rocate “闪耀”; 亚美尼亚语 lois “光”, lusin “月亮”; 希腊语 leukos “明亮的,闪亮的,白色的”; 拉丁语 lucere “发光”, lux “光”, lucidus “清晰的”; 古斯拉夫语 luci “光”; 立陶宛语 laukas “苍白的”; 威尔士语 llug “微光,闪烁”; 古爱尔兰语 loche “闪电”, luchair “亮度”; 赫梯语 lukezi “明亮的”; 古英语 leht, leoht “光,日光; 精神上的启示”,德语 Licht,哥特语 liuhaþ “光”。