Oxford Advanced American Dictionary

Definition of lightly adverb from the Oxford Advanced Learner's Dictionary

 Oxford3000

lightly

adverb
lightly pronunciation English ˈlaɪtli lightly pronunciation American ˈlaɪtli
 
1 gently; with very little force or effortHe kissed her lightly on the cheek.She ran lightly up the stairs.2 to a small degree; not muchIt began to snow lightly.She tended to sleep lightly nowadays (= it was easy to disturb her).I try to eat lightly (= not to eat heavy or greasy food).3 in a way that sounds as though you are not particularly worried or interested
Synonym
nonchalantly‘I'll be all right,’ he said lightly.4 without being seriously consideredThis is not a problem we should take lightly.Such fears should not be dismissed lightly.
Idioms

get off/be let off lightly

(informal) to be punished or treated in a way that is less severe than you deserve or may have expectedHe got off lightly with a small fine.The children were let off lightly.