Subcontinent

I found a number of definitions for this.

In a geographic sense, the general idea is that a subcontinent is a large area of land that’s not an entire continent, but that is somehow demarked from the rest of the continent by natural features, or, in some cases, the border of a tectonic plate.

Examples:

• India is not a continent, but it’s bordered on the north and west by large mountain ranges (the Himilayas and the Hindu Kush), and by the ocean in the south.
• Greenland is not a continent, but it’s an island, so there are natural borders.
• The Arabian Peninsula is connected to Asia, but is surrounded by water on three sides, and a desert to the north.

This Quora question provides examples of the confusion: What are examples of subcontinents?

Note that lots of people there are arguing that the words means something politically, not geographically. Also, people arguing that Europe is actually a subcontinent:

Calling Indian subcontinent a “Subcontinent” and Europe a full continent is pure euro-centric arrogance and has nothing to do with logic.

[…] Europe is actually a subcontinent. It is a continent only for political reasons.

Throughout those answers, a couple of things become apparent:

• Many people arguing that India is the only true subcontinent (one person said that “subcontinent” is just another way of saying “India”)
• Other people stating that there’s not strict definition (some guy pointed out that Pluto was once a planet…)
• Other people arguing that a subcontinent is basically just a large section of a continent (lots of people saying that the United States is a subcontinent of North America)

Next up, clearly: what’s the strict definition of a continent? (Done, here)