offhand

Short definition from Wiktionary

Adjective

1. 1
   Without planning or thinking ahead.
2. 2
   Careless; without sufficient thought or consideration.
3. 3
   Curt, abrupt, unfriendly.

Adverb

1. 1
   Right away, immediately, without thinking about it.
2. 2
   In an abrupt or unfriendly manner.