The word ‘ancient’ is often used inappropriately in relation to the Gaelic language, but the name of the River Tay is undeniably ancient.
The earliest source for the name is contained in Ptolemy’s Geography, compiled some time between 140 and 150 AD, where it is recorded as Taoua. Several derivations for this name have been offered, but none have been universally accepted.
In modern Gaelic, it is called Uisge Tatha or Abhainn Tatha ‘the water of Tay’ or ‘the river of Tay’. Likewise, Loch Tay is Loch Tatha whilst someone living in Strathtay is known as a Tathach, a ‘Tay man’. There is a Gaelic saying: Tatha mhòr nan tonn, bheir i sgrìob lom air Peairt ‘Great Tay of the waves, she will sweep Perth bare.’ In this saying, Tatha is in the feminine gender, just as it was in Ptolemy’s form.
For more information on this name visit Ainmean-Àite na h-Alba