ad Taum c.98 Tacitus Agricola 22, 1 [variant reading Tanaum (for Tauaum); ‘the nations laid waste as far as the Tay, that is the name of an estuary’ (vastatis usque ad Taum, aestuario nomen est, nationibus)]
Taoúa potamoû ekbolaí c.150 Ptolemy [from Isaac 2005, 204; Greek potamoû ekbolaí ‘river-mouth, estuary’]
túatha Toí c.600 Clancy and Márkus 1995, 104 [Amra Choluimb Chille §i: ‘the tribes of the Tay’; thus Clancy and Márkus, as in the 12th-c. Lebor na hUidre MS; Bernard and Atkinson render MS T of ILH at this point tuatha Toi, with no accents (i, 169)]
ic Toí c.600 Clancy and Márkus 1995, 112 [Amra Choluimb Chille §viii: ‘his <Columba’s> blessing turned them, the mouths of the fierce ones who lived on the Tay (batar ic Toí), to the will of the King’; as in the Lebor na hUidre MS; MS T of ILH has ‘ic Toi’ with no accent (i, 179)]
Taba c.7 th century Rivet and Smith 1979, 470 (Ravenna Cosmography) [also the form given in Isaac 2005, 204; Rivet and Smith (loc. cit.) note that though Taba is among the ‘diversa loca’ rather than rivers, ‘presumably on the map-source Taba – with Vulgar Latin b for v as often – was written along the inland course of the river and misread as a habitation name’]
Tóe c.1060 Anderson 1929, 50 [from ‘Prophecy of Berchán’; see Abertay FPC, below]
na tuatha batar im Thai 11 /12th century ILH i, 169 [‘the tribes that were on the Tay’; gloss on the Amra Choluim Cille; thus also 12th-century Lebor na hUidre]
arrd-rig Toí 11 /12th century ILH i, 179 [‘the high king of the Tay’; gloss on Amra Choluim Cille; thus also in the same gloss in 12th-century Lebor na hUidre, ‘ardríg Toí’]
Tey 1127 x 1131 David I Chrs. no. 33 [Dunf. Reg. no. 1; David I confirms to Dunfermline Abbey ‘half the hides, tallow and suet from all the animals killed at the feasts held in Stirling and between the Forth and the Tay’ (medietatem coriorum et seporum et sagiminis omnium bestiarum que occidentur ad festivitates tenendas in Strivelin et inter Forth et Tey)]
in aqua de Thei 1140 St A. Lib. 183 [= David I Chrs. no. 88; David grants to St Andrews Priory ‘the draught of one net in the River Tay’ (tractum unius retis)]
Tay 1150 x 1152 Dunf. Reg. no. 2 [= David I Chrs. no. 172; renewal of grant of Dunf. Reg. no. 1, as above]
aqua de Pert 1153 x 1159 St A. Lib. 197 [= RRS i no. 119; grant, as per St A. Lib. 183 (see above), of draught of one net in ‘the water of Perth’(i.e Tay)]
aqu<a> de Tei 1153 x 1159 RRS i no. 137 [Malcolm IV grants to monks of Rhynd (Rindelgros) PER teind of the fishings ‘of the waters of Tay and Earn’ (aquarum de Tei et Ern)]
Tay 1154 x 1159 RRS i no. 118 [= Dunf. Reg. no. 35]
Tay 1161 x 1164 RRS i no. 214 [Malcolm IV informs justice of Fife and sheriffs of Dunfermline and Clackmannan et al. that he has granted half his fat of the whales or large fish (crespias) caught between Forth and Tay to Dunfermline Abbey, for lights burning before the altars of that church]
duo recia super Tey 1163 x 1164 RRS i no. 243 [‘two nets’ (Scone Abbey)]
Tay 1165 x 1168 RRS ii no. 30 [= Dunf. Reg. no. 50; once Tay, once Thay]
e aquilone fluminis de Tei 1165 x 1174 RRS ii no. 18 [‘on north of river Tay’]
Thei 1173 x 1178 RRS ii no. 165 [king to the canons of Scone to receive the teind of the catch of fish ‘from all my fishings which are on the Tay facing the territory of Scone, Kinnoull Hill and Kinfauns’ (de omnibus piscationibus meis que sunt super Thei contra territorium Scon’, Cragh et Kinfathenes)]
Tae c.1180 s De Situ Albanie (Anderson 1980, 241) [14th c. copy]
They 1190 x 1195 RRS ii no. 363 [= Lind. Cart. no. 138; ‘the burn  that runs down from the big loch into the Tay’ (rivuli descendentis de magnu lacu usque in They)]
Tay 1790s OSA, 665 [washing the northern edge of the parish, it is called locally the Broad Water]
In 1926 W. J. Watson discussed this name at length, stating that in modern Gaelic the river is called Tatha, a regular Scottish Gaelicisation of an original long-vowelled Tōe, which he regards as ‘doubtless primarily the name of a goddess, the Silent One. The corresponding Welsh term is taw, silent, silence; and the Welsh name for our Tay was Tawy.’ (1926, 50–1). K. H. Jackson cautiously supported this derivation from *taus- ‘silent, quiet’, Welsh taw, concluding that ‘the Tay may possibly be from *Tausos, *Tausā’ (1953, 369–70, 522, quoted in Isaac 2005, 204).
In 1979 Rivet and Smith noted that both Pokorny and Nicolaisen had dismissed the ‘silent’ root, instead seeing the name as ‘one of a very large family – from the Indo-European root *ta- *t«- ‘fließen’ [German ‘to flow’] with the third type of consonantal development in Nicolaisen’s classification ... this Celtic Tauā or Taujā > Tay, Taw, meaning simply ‘flowing one, river’ (1979, 470).
In a recent discussion of this name, Graham Isaac surveys all the evidence, as a result of which he conclusively dismisses the possibility that the name contains the ‘silent’ root, both on linguistic and semantic grounds. Furthermore he declares the Indo-European root *ta- ‘flow’ is ‘a ghost’, it being actually *teh2- ‘thaw, melt’, but gives only very cautious support to ‘thawing, thawed river’, ‘[p]erhaps a river which swells especially noticeably in spring thaw?’, finally concluding that the Indo-European ‘affiliation and Celticity of Taoua are doubtful’ (2005, 204).
The Longer Foundation Legend of St Andrews (see PNF 3, App. 1, for edition and translation) refers to the Firth of Tay as Slethemur. This is probably a Pictish name. The second element is presumably Pictish *mor (cognate with Old Welsh/British *mori) or possibly Gaelic muir ‘sea, arm of the sea’. For the perception of the estuaries of the larger Scottish rivers as ‘seas’, see references under Forth (Volume 1, 39–40), which include merin Iodeo, Mur nGuidna, Mur nGuidan, Ihwdenemur, all referring to the Firth of Forth, and all of which names seem to contain versions of the Pictish or British word for ‘sea’. The first or specific element of Slethemur is unclear, but it may perhaps be a Pictish word related either to OG sleith, a verbal noun from selid ‘creeps’ (DIL); or to the Perthshire G sleithe (f.) ‘section, division, cutting’ (Dwelly).
In the earliest charters the Tay plays two distinct roles: one as a boundary, the other as an economic resource.
This place-name appeared in printed volume 4