| Noun | 1. | lightening - descent of the uterus into the pelvic cavity that occurs late in pregnancy; the fetus is said to have dropped descent - a movement downward |
| 2. | lightening - changing to a lighter color change of color - an act that changes the light that something reflects bleach - the act of whitening something by bleaching it (exposing it to sunlight or using a chemical bleaching agent) |