1
- make or become lighter in weight, pressure, or severity减轻（重量, 压力或严重程度）, （重量, 压力或严重程度）变轻：
with obj. efforts to lighten the burden of regulation减轻调控工作负担的尝试
no obj. the strain had lightened.压力已经减轻了。
1.1
- make or become more cheerful or less serious使轻松愉快：
with obj. she attempted a joke to lighten the atmosphere她试图开个玩笑让气氛轻松起来
no obj. Robbie felt her spirits lighten a little.罗比觉得她的情绪放松了一点儿。
1
- make or become lighter or brighter（使）变得更亮：
no obj. the sky began to lighten in the east东方的天空开始变得越发明亮了
with obj. she had lightened her hair她已经把头发弄亮了些。
1.1
- with obj. archaic enlighten spiritually〈古〉启迪, 开导：
now the Lord lighten thee, thou art a great fool.
汝大愚矣, 愿主多多开导。
2
- no obj.（it lightens, it is lightening,等）rare emit flashes of lightning; flash with lightning〈罕〉闪电划过：
it thundered and lightened.
电闪雷鸣。