What is the word "sub" short for in a sub sandwich?

In Louisiana we eat all kinds frenchbreads rolls pistolettes croissants to make subs, but the best ONE is, when its called a POBOY🥖🥖

When I was younger, I could eat two foot long subs in one sitting. Never gained a pound. Not so anymore. My wife can, though...

Spuckie? Where?

I love Cheesesteak Subs with French Fries and Soda it’s so good

Hoagie. A Philadelphia only term