brainless

He made a brainless decision without considering the consequences.

She's not brainless, just a bit absent-minded sometimes.

Don't be brainless, think before you act!

The brainless mistake cost him his job.

He's so brainless, always forgetting important dates.

It was a brainless move to invest all his money in one stock.

The brainless act of vandalism caused damage to the property.

She's not brainless, just inexperienced in this field.

I can't believe I made such a brainless mistake on the exam.

His brainless comment offended many people in the room.