Definitions of offhand:

• adjective:   casually thoughtless or inconsiderate

  Example: "An offhand manner"

• adjective:   with little or no preparation or forethought

  Example: "Offhand excuses"

• adverb:   in a casually inconsiderate manner

  Example: "Replied offhand, his mind a million miles away"

• adverb:   without previous thought or preparation

  Example: "Couldn't give the figures offhand"