Past has 11 different meanings across 4 categories:
a earlier period in someone's life (especially one that they have reason to keep secret)
"reporters dug into the candidate's past"
a verb tense that expresses actions or states in the past
"The story opens by describing how the hero lost his sword before he found it again."
The period of time that has already happened, in contrast to the present and the future.
"Looking back at our past, I realize how much we've grown together since those early days."
In plain English: The past is everything that has already happened before now.
Usage: Use "past" as a noun to refer to history or events that have already occurred, often appearing after verbs like "look into" or phrases such as "the past few years." Avoid using it as a verb form of "pass," which should be spelled separately.
simple past tense and past participle of pass
"I passed the test yesterday, so I am very happy about my grade now."
In plain English: To past something means to move it from one side of an opening to the other, like throwing a ball through a hoop.
"The team will not past the halfway point before sunset."
Usage: Use "past" as a verb only when describing the action of going by or happening after a specific time, though in modern English this usage is often replaced by "passed." Most frequently, treat it as an adjective meaning having gone by rather than using it as a main verb.
earlier than the present time; no longer current
"time past"
"his youth is past"
"this past Thursday"
"the past year"
Having already happened; in the past; finished.
"She kept talking about her childhood as if it were a living memory, but those days are long gone and can never be changed."
In plain English: Past means something that happened before now and is no longer happening.
"The past year has been very busy for everyone."
Usage: Use "past" as an adjective only when describing something that has already occurred or is no longer current, such as "a past president." Do not use it to describe time duration or position, which requires the noun form or preposition "past."
In a direction that passes.
"The car drove past our house without stopping."
In plain English: Past means happening before now.
"The train has already passed us."
Usage: Use "past" as an adverb to indicate movement beyond a specific point or person in time or space, such as when someone walks past you. It functions without a following noun phrase, unlike the preposition "past," which must be followed by one.
Beyond in place or quantity
"The trail disappeared into the dense forest, leaving no path beyond that point."
The word "past" comes from the Middle English phrase passed, which was the past participle of the verb meaning "to go by." It entered modern usage as an adjective describing something that has gone before or is no longer present.