Yes, Monday is considered a proper noun. Proper nouns are specific names for particular people, places, or things. In this case, ‘Monday’ refers to a specific day of the week and is capitalized to denote its status as a proper noun.
It’s important to note that proper nouns are always capitalized in English. This distinguishes them from common nouns, which refer to general items or concepts. For example, while ‘day’ is a common noun, ‘Monday’ is a specific instance of that common noun, thus qualifying it as a proper noun.