aḥaron

This is the word for whatever comes after. The single idea underneath it is following behind something else, and the context decides what that something is. Often it is counting toward an end: the last day, the last man in a line, the final one of a set. Often it looks ahead in time: a later day, the time to come, the people who will live after us. And often it simply means after, as opposed to what came before, which is why English Bibles so frequently pair it with the word for first or former.

These shades are one idea seen from different angles. Being last in a count, being later in time, and being the one who comes after are all the same picture: standing behind what has already gone ahead. The same word that marks the last day of a feast can name a future generation, and can describe the second of two things set side by side.

The word carries real weight when the prophet Isaiah has God call himself the first and the last. There it is not saying God arrives at the end of a line; it is saying God is there after everything, just as he was there before everything, with nothing outlasting him. The same reach forward shows up wherever the word names the generations still to come, the people who will tell the next ones what God has done.

This meaning keeps the same root idea of being behind, but in space rather than in time. Someone giving directions in ancient Israel faced the sunrise, so the back was the west. That is why the same word that means hinder also means western, and why the great sea behind a person facing east, the Mediterranean, is called the western sea.

The plain spatial use is simpler still: the one at the rear, the hindmost in a march or a line, the people placed at the back. When Jacob arranges his family to meet his brother, he puts the wife and son he loves most at the very back, out of harm's way, and this is the word for it.

The link between the two meanings is worth holding onto. Whether a thing is behind you in space or behind the present moment in time, Hebrew reaches for this one word, and only the surrounding words tell you which is meant.