Without planning or thinking ahead.
She gave an offhand speech.
Careless; without sufficient thought or consideration.
He doesn't realise how hurtful his offhand remarks can be.
Curt, abrupt, unfriendly.
She was quite offhand with me yesterday.
Right away, immediately, without thinking about it.
Offhand, I'd guess that that's a yellow-bellied sapsucker.
In an offhand manner.