An isthmus is a strip of land that connects two larger areas of land. It typically has water on either side. From what I have heard, there are currently 56 isthmuses on Earth. I wouldn't say they are common, but they are definitely not rare.
Some words that start with 'ist-' include: Istanbul, isthmus, isthmian, isolation, istle, isthmuses, isthmians, isthmuses, and isolationism.
One of the most famous isthmuses is the Isthmus of Panama. Some other isthmuses are the Isthmus of Suez, the Isthmus of Kra, the Isthmus of Corinth... Check Wikipedia for more. :)
panama ithsmus
isthmuses
Nobody makes isthmuses. They are naturally-occurring geological formations.
Isthmuses can be formed from erosion or deposition or even volcanic ash!
See Wikipedia - List of Isthmuses http://en.wikipedia.org/wiki/List_of_isthmuses
Metro Manila in the Philippines and the center of the town of Kushimoto in Japan are situated on isthmuses.
The plural of isthmus is accepted as either isthmuses or isthmi.
An isthmus is a strip of land that is very narrow and it links two larger areas of land. Isthmuses are surrounded by the sea on either side.
Isthmi is plural. There are actually two plural forms. I will list them from singular to plural. Isthmus - Singular Isthmi - Plural Isthmuses - Plural
Thailand