I've always found it odd that English, which otherwise is fairly rich vocabulary-wise, does not have a specific word for this. In Danish, we have 'dag' (day), '

I've always found it odd that English, which otherwise is fairly rich vocabulary-wise, does not have a specific word for this. In Danish, we have 'dag' (day), 'nat' (night), and 'døgn' (a day and a night). A 'døgn' contains all the leap seconds that may be necessary.