Source : Webster's Revised Unabridged Dictionary (1913)

Offhand \Off"hand`\, a.
   Instant; ready; extemporaneous; as, an offhand speech;
   offhand excuses. -- adv. In an offhand manner; as, he replied
   offhand.

Source : WordNet®

offhand
     adv 1: without previous thought or preparation; "couldn't give the
            figures offhand"; "we decided offhand to go to
            Canada"; "she had made these remarks offhandedly"
            [syn: {offhanded}, {offhandedly}]
     2: in a casually inconsiderate manner; "replied offhand, his
        mind a million miles away"; "she threw him over
        offhandedly without even a Dear-John letter" [syn: {offhanded},
         {offhandedly}]

offhand
     adj 1: with little or no preparation or forethought; "his ad-lib
            comments showed poor judgment"; "an extemporaneous
            piano recital"; "an extemporary lecture"; "an
            extempore skit"; "an impromptu speech"; "offhand
            excuses"; "trying to sound offhanded and reassuring";
            "an off-the-cuff toast"; "a few unrehearsed comments"
            [syn: {ad-lib}, {extemporaneous}, {extemporary}, {extempore},
             {impromptu}, {offhanded}, {off-the-cuff}, {unrehearsed}]
     2: casually thoughtless or inconsiderate; "an offhand manner";
        "she treated most men with offhand contempt" [syn: {offhanded}]