a year: one full cycle of twelve months as a unit for measuring time
This is the ordinary word for a year, a single turn of the calendar used to count how long something lasts or how old someone is. The New Testament reaches for it in three everyday ways, and all three are the same idea of a year, just put to different work.
Most often it counts duration: how long a condition, a promise, or an era has run. A woman is sick for twelve years, Israel wanders forty years, the binding of Satan lasts a thousand years. It also counts age, almost always paired with a number to tell us how old a person is, as when Jesus is about thirty years old when he begins his ministry. Less often it fixes a date, marking the particular year in which an event happened, such as the fifteenth year of a Roman emperor's reign.
Because a year is a plain, agreed unit, the word carries no hidden freight. It simply names the span. The interest in any given verse comes from the number attached to it, not from the word itself.