Definitions
1.nounThe day after the present day.
2.adverbOn the day after the present day.
3.adverbAt some point in the future; later on"If you don't get your life on track today, you're going to be very sorry tomorrow."
4.adverb(possibly obsolete) On next (period of time other than a day, such as a week or a month), following the present (period of time).
5.adverbOn the next day (following some date in the past).