If you are sitting or standing upright, you are sitting or standing with your back straight, rather than bending or lying down.

An upright vacuum cleaner or freezer is tall rather than wide.

An upright chair has a straight back and no arms.

You can refer to vertical posts or the vertical parts of an object as uprights .

You can describe people as upright when they are careful to follow acceptable rules of behaviour and behave in a moral way.