Source : Webster's Revised Unabridged Dictionary (1913)

Lightly \Light"ly\, adv.
   1. With little weight; with little force; as, to tread
      lightly; to press lightly.

            Yet shall thy grave with rising flowers be drest,
            And the green turf lie lightly on thy breast.
                                                  --Pope.

            Him thus intent Ithuriel with his spear Touched
            lightly.                              --Milton.

   2. Swiftly; nimbly; with agility.

            So mikle was that barge, it might not lightly sail.
                                                  --R. of
                                                  Brunne.

            Watch what thou seest and lightly bring me word.
                                                  --Tennyson.

   3. Without deep impression.

            The soft ideas of the cheerful note, Lightly
            received, were easily forgot.         --Prior.

   4. In a small degree; slightly; not severely.

            At the first he lightly afflicted the land of
            Zebulun . . . and afterward did more grievously
            afflict her.                          --Is. ix. 1.

   5. With little effort or difficulty; easily; readily.

            That lightly come, shall lightly go.  --Old Proverb.

            They come lightly by the malt, and need not spare
            it.                                   --Sir W.
                                                  Scott.

   6. Without reason, or for reasons of little weight.

            Flatter not the rich, neither do thou willingly or
            lightly appear before great personages. --Jer.
                                                  Taylor.

   7. Commonly; usually. [Obs.] --Bp. Fisher.

            The great thieves of a state are lightly the
            officers of the crown.                --B. Jonson.

   8. Without dejection; cheerfully. ``Seeming to bear it
      lightly.'' --Shak.

   9. Without heed or care; with levity; gayly; airily.

            Matrimony . . . is not by any to be enterprised, nor
            taken in hand, unadvisedly, lightly, or wantonly.
                                                  --Book of
                                                  Common Prayer
                                                  [Eng. Ed.].

   10. Not chastely; wantonly. --Swift.

Source : WordNet®

lightly
     adv 1: without good reason; "one cannot say such things lightly"
     2: with few burdens; "experienced travellers travel light"
        [syn: {light}]
     3: with little weight or force; "she kissed him lightly on the
        forehead" [syn: {softly}, {gently}]
     4: indulging with temperance; "we eat lightly in the morning"
        [ant: {heavily}]
     5: with indifference or without dejection; "he took it lightly"
     6: in a small quantity or extent; "spread the margarine thinly
        over the meat"; "apply paint lightly" [syn: {thinly}]
        [ant: {thickly}]
     7: to a slight degree; "her speech is only lightly accented"