Tarn is a word used in the Vedran language. In the series it could be referring to:
- Tarn-Vedra, the home planet of the Vedrans and the long-lost and almost mythical capital of the Systems Commonwealth.
- Vishna-Tarn, the capital city of the planet Tarn-Vedra.
- The word tarn is from the Middle English "terne", describing a small mountain lake or pool, particularly one in a cirque. It comes from the Old Norse "tjǫrn", a pond or pool.