What is the Nouns for past?

"Past" can be any of four parts of speech:

• Adverb: to describe the position of a verb, e.g. The parade marched past.
• Adjective: to describe a noun that has gone by, e.g. The past year has been an interesting one.
• Noun: to explain a time, e.g. In the past, goods had to be transported by horse and cart.
• Preposition: to begin a phrase explaining a time or place, e.g. The runner could not get past the first obstacle; It is half past eight.