A podcast is a recorded program of talks, music, etc. made available over the Internet as a file that can be downloaded to a computer or portable device. https://www.allearsenglish.com/episodes/

It is a modification of the word "broadcast." "Pod" comes from the brand name "iPod," Apple's music playing device. In the old days, people listened to radio broadcasts. Often they were on a regular schedule--say, a half an hour a week, always at 3:30 p.m. Tuesdays. Podcasts are somewhat in the style of a radio broadcast. They aren't streamed. You can listen to them any time. But they are often produced as a regular series. For example, there is a program on the radio called "Wait, Wait, Don't Tell Me." It is a humorous quiz show about the news. I can listen to it on the radio. I can tune it in when it is being broadcast. Sometimes I do that. They also make it available as a podcast. My cell phone has a piece of software, a podcast player, that is installed on it. I "subscribe" to "Wait, Wait, Don't Tell Me." Every week, the software downloads an .mp3 file of the program. Instead of listening to a weekly broadcast on the radio, I listen to a weekly podcast on my cell phone.