Is ONT a modem or router?

Excuse me, but I'm a bit confused about the term "ONT" in the context of technology. Could you please clarify if "ONT" stands for a modem or a router? As far as my knowledge goes, these two devices serve different purposes within a network setup. A modem, typically, converts digital signals to analog signals for transmission over phone lines or cables, while a router manages the Flow of data between multiple devices on a local network and the internet. So, is "ONT" perhaps referring to a device that combines the functionalities of both a modem and a router, or is it something completely different? I'd appreciate it if you could provide some clarification.