a sufficient amount: as much as is needed to meet a need, a task, or a measure
This word names sufficiency, the amount that answers a need. It almost never stands alone as a plain noun; it lives inside a short phrase built with a small attached preposition, and that preposition steers its shade, so a reader has to watch the whole phrase, not the one word.
At its base it means simply enough: enough material to finish the work, enough means to afford a lamb, enough milk for the household. Pressed a little further it becomes one's fill or more than enough, as when the honey-eater is warned to stop at his fill, or when the promised blessing pours out until there is no more room for it.
Two of the attached prepositions carry it in surprising directions. Joined with the word for "according to," it means in proportion to a fixed measure, as when the number of blows is matched to the size of the offense. Joined with the word for "from," it turns into a marker of time, meaning as often as, from year to year, whenever. The single thread running through all of these is a measured amount, or a measured interval, that recurs.