Yes, ‘tomorrow’ is an adverb. In English grammar, adverbs are words that modify verbs, adjectives, or other adverbs, typically expressing time, manner, place, or degree. ‘Tomorrow’ specifically indicates a time relative to the present day, suggesting the day that follows the current one.
For example, in the sentence ‘I will go to the store tomorrow,’ ‘tomorrow’ modifies the verb ‘go’ by specifying when the action will take place. This temporal quality is what categorizes ‘tomorrow’ as an adverb.
It is interesting to note that while ‘tomorrow’ can function as an adverb, it can also be used in other forms, such as a noun when referring to the day itself. However, in its adverbial use, it clearly serves to provide information about the timing of an action.