Why is the word 'Poke' obsolete?

I heard somewhere there was a word that in english translated to 3 words: pocket (small bag), pouch (regular-sized bag), and poke (large bag). I also heard that poke is now obsolete. This seems to be true, so why is it obsolete/why don't people use it?

Edit

I think I heard that it was obsolete in America or something like that.

Meanings of words change over the years. Words fall out of use, or are reapplied, or new words are invented. The "why" is usually just because the people using the language are spending their time speaking about different things than they used to, and the language adapts to suit their needs.

A pocket is no longer a small bag; it's usually used to mean a bag built into a piece of clothing to conveniently carry small objects. It can also sometimes refer to other pocketlike structures.

A pouch now usually connotes a particular kind of bag, typically with a narrowed or drawstring neck, not necessarily of any particular size. It can also refer to other pouchlike structures.

A poke ... well, these days almost nobody uses that kind of large bag often enough to need a short name for it. It's simply called "a large bag", or described by its purpose or shape or specific size. As Erik mentioned, the only current use of the word that most of us have heard is "buying a pig in a poke" -- and many people who use that phrase have no idea of its origin.

It appears that the use of 'poke' meaning a 'bag' has always been mainly regional both in US an UK. Ngran shows that both the expression a pig in the poke and in a poke have actually never gained much currency though still in use.

Poke:

n. Chiefly Southern U.S.:

Regional Note:

The noun poke meaning a bag or sack dates from the 14th century in English. In many parts of Scotland poke means a little paper bag for carrying purchases or a cone-shaped piece of paper for an ice-cream cone. The Oxford English Dictionary gives similar forms in other languages: Icelandic poki, Gaelic poc or poca, and French poche.

I grew up in Chicago in a neighborhood where almost everyone's parents or grandparents were from Tennessee, Kentucky and West Virginia. We commonly referred to taking our bag lunch to school as a lunch in a poke. And the word "poke" was very common when referring to a bag. The Appalachian dialect is very conservative and tends to be passed on for a few generations. And the words are often passed on to non-Appalachian speakers. My kids know that a poke is bag. So I wouldn't say it's obsolete.