lightening
  照明; 發光
  light·en·ing /ˈlaɪtṇɪŋ, ˈlaɪtnɪŋ/ 名詞
  胎兒下降感
  Light·en v. i. [imp. & p. p. Lightened p. pr. & vb. n. Lightening.]
  1. To burst forth or dart, as lightning; to shine with, or like, lightning; to display a flash or flashes of lightning; to flash.
  This dreadful night,
  That thunders, lightens, opens graves, and roars
  As doth the lion.   --Shak.
  2. To grow lighter; to become less dark or lowering; to brighten; to clear, as the sky.
  lightening
       n 1: descent of the uterus into the pelvic cavity that occurs
            late in pregnancy; the fetus is said to have dropped
       2: changing to a lighter color [syn: whitening]