1. someone who gets angry or excited easily and acts without thinking carefully
someone can be a bit of a hot head
If someone is 'a hot head', they are very likely to get angry easily. You might imagine their head heating up and exploding with anger! Likewise, if you're 'hot-headed' or 'a hot-headed person', you are prone to losing your temper or acting without thinking things through. You might hear this in any context, social or professional.