A noun is a person, place, thing, or idea. In the case of the word 'tomorrow', it is 'thing', Referring to the period of time following today.
1. Tomorrow won't be easy.
2. The future is tomorrow.
Possessive forms of the word (e.g. tomorrow’s) can take on subtle changes in meaning that can’t always be predicted. For instance, 'tomorrow’s test' could mean the test that takes place the day after today, but it could also mean a particular test (i.e. belonging to tomorrow) that takes place sometime in the future.
An adverb is a word or phrase that modifies a verb, an adjective, or another adverb. In the case of the word 'tomorrow', it modifies verbs to refer to what will happen in the future.
when used as an adverb include capitalisation (tomorrow, but not Tomorrow).
1. I'll finish the work tomorrow.
2. She will come tomorrow.
3. We will make a plan tomorrow.
As an adverb, 'tomorrow' can be used to refer to a specific or indefinite period of time in the future. For instance, 'I’ll finish this tomorrow' could mean today or sometime within the next few days, while 'I’ll finish this next week tomorrow' would imply that the task will be completed on a certain day within the following week.