What are the opposite words for 15th?

The word "15th" does not have an antonym as it is a specific numerical designation for a day or position within a sequence. Antonyms are words that have opposite meanings such as hot and cold, happy and sad, or love and hate. The opposite of 15th would be a different numerical position such as 1st, 2nd, 3rd, 4th, etc. or the absence of a specific day or position within a sequence. While 15th may not have an antonym in the traditional sense, its opposite could be seen as any other day or position that is not the 15th.

Antonym of the day

dry, pass up, underwhelm.