v1.0
Published 01/10/24
tiùrr m. (occasionally f.
E.g. MacPhàrlain 1973, 76: [a]m bàrr na tiùrr, 19: a dh’uachdar na tiùrra.
) [tʲʰuːɍ], gen. idem or -a -[ə], or tiùrra, gen. idem, 
Cf. (Glengarry) [tciuR] (Dieckhoff 1932), (Lewis) /t’uːR(ə)/ (Oftedal 1956, 359), (Gairloch) [t’ʰʲuːʀ] (Wentworth 2003, s.v. tide-mark).
in the sense ‘beach out of reach of the sea’ is derived by MacBain (1896: tiurr) from Norse eyrr ‘a gravelly bank by a river or a promontory’, on the basis that initial t- is the result of mutation of an initial vowel following the Gaelic radical masculine article (an t-). Henderson (1910, 147: tiurr, 218: tiūrr, an t-iūrr) and McDonald (2009, 352) concur; indeed, Henderson (p. 147) derives the variant form SG siùrra 
Via back-formation after mutation of initial s- after the (for example) dative Gaelic article, with an tiùrra taken for the phonetically identical an t-siùrr(a); cf. SG tìde ‘time → weather’ ~ sìde ‘weather’ (< MScots tid(e) < MEng. tīd(e)) (for further examples, see Calder 1972, 67).
from the same source. However, ON eyrr is unlikely to yield SG *iùrr *[juːɍ] (contrast SG Èire < ON *Eyri dat., s.v. faoilinn).
Oftedal (1962, 119) opines that siùrra (tiùrr) ‘cannot be satisfactorily explained as being of Norse origin’.
MacLennan (1925), on the other hand, takes tiùrr to be a by-form of SG tòrr, but, despite the broadly comparable doublet in SG tiobar (EG tipra) and (the etymologically distinct) tobar (EG topar), both meaning 'well; spring' (see Watson 1926, 503–04), the semantic ranges of tiùrr and tòrr are significantly different. SG tòrr, which appears to go back ultimately to Lat. turris ‘tower’ 
MacBain 1911; MacLennan 1925.
(> EG tor ‘tower; fortified building’ (eDIL˄)), has the senses ‘hill; heap; a large amount’ (s.vv. dùn, starrag), while SG tiùrr has a number of forms and senses.
A. SG siùrra
The Colonsay-Mull tale ‘Ridire na Sgiatha Deirge’ (Campbell 1860, 466) includes the clauses ... ’s cha b’ e do chuid mac leibideach-sa, a bhiodh ’nan sìneadh an siùrra feamann nur a bhiodh eisean a’ dol air ghaisge, which is translated (p. 454) ‘... and it was not thy set of shambling sons, that would be stretched as seaweed seekers when he was gone to heroism’. Dwelly (1911, s.v. siùrra feamann) points out that ‘seaweed seekers’ is a mistranslation and that siùrra feamann refers to ‘wrack along the watermark’.
B. SG tiùrr, tiùrra
Dwelly 1911, s.v. tiùrr: ‘beach out of reach of the sea; seaware cast up by the sea at high-water mark (west coast of Ross); mark, stamp, impress; mark of the sea on the shore; refuse left by the tide on the beach: tiùrr na mara “high-water mark”’; MacLennan 1925, s.v. idem: [tioor] ‘heap; high-water mark, usually heaped up sand or shingle or seaware; broken seaware cast up by the tide’; Matheson 1938, 373, s.v. idem: ‘heap, seaware cast up by the sea at high-water mark’ (from a poem by John MacCodrum (1693–1779, North Uist): pl. (ibid., 176–77, line 2577) ’na thiùrrannan ‘in heaps’); Oftedal 1956, 359, s.v. idem: /t’uːR(ə)/ ‘(large) heap’: tiùrr gainmhich ‘sand-bank’ (Lewis); 
LASID IV, 250, Item 240, gives (Lewis) [t´ʃuːrə tɔːr] for ‘manure heap’.
MacIntyre 1968, 221, lines 6441–42: feadh tiùrra na tràghad, editor’s index (p. 416, s.v. tiùrr): ‘seaweed at high-water mark’ (South Uist); McDonald 1972, s.v. tiùr(r): ‘top of high tide’ (South Uist); Wentworth 2003, s.v. tide-mark: tiùrr [t’ʰʲuːʀ] ‘tide-mark’ (Gairloch); AFB˄, s.v. tiùrr: /tʲuːR/ ‘high-water mark (spec[ifically] beach/shore above the high-water mark); flotsam and jetsam; heap, pile’ (Outer Hebrides, Skye, Tiree); Mac Gill-Fhinnein 2009, 132, s.v. tiurr: ‘barr láin, snáth mara’ (South Uist); Faclan bhon t-Sluagh˄, s.vv. tiurr, tiùrr, tiurra, tiùrra: ‘seaweed, flotsam, strand’ (South Uist), ‘heap’ (Lewis), ‘deposit of seaweed etc. left at high tide’ (North Uist); (pl.) tiùrrachan brùchd ‘heaps of seaweed’ (Lewis); tiùrr feamainn ‘heap of seaweed’ (Skye); tiùrr an làin ‘what was left after high tide’ (Harris); ann an tiùrr an làn [sic] ‘ann am beul na mara far am biodh am muir a’ fàgail a h-uile seòrsa nì’ (Lewis); os an tiùrr ‘above high-tide mark’ (Strathglass); in Glengarry, pronunciation falls in line with development in similar native words, with lengthening of u after C´ and before -rr in the form of diphthongisation: 
This lengthening is discussed in, for example, O’Rahilly 1976, 49–52; Ó Baoill 1990, 131; Cox 2000, 214–15.
Dieckhoff 1932, s.v. tiurr: [tciuR] ‘the beach down to the line where seaweeds are washed up’, cf. SG ciurr [k´iuR] ‘[to] hurt’ (ibid.).
C. SG tiùr, tiùir, tiubhair
Alexander Carmichael (CG II, 342) lists tiur, 
Noted in MacBain 1911, s.v. tiurr.
tiuir and disyllabic tiubhir ‘mark, stamp, impress; the mark of the sea upon the shore; the refuse left by the tide upon the beach’ – these are spelt tiùr, tiùir and tiubhair by Angus Matheson in CG VI, 266: ‘some of these words at least = tiurr [sic]’; Dwelly (1911) cross-references tiur to tiurr (leg. tiùrr); McDonald (1972) cites the variants tiùr, tiùrr ‘top of high tide’, also tiubhar ‘sea weed left by high tide’ (South Uist).
D. SG teòir, teòr, teòrr
McDonald (1972, South Uist) lists teòir in the context of airgiod (sic) teòir ‘shore money’, comparing tiùr (C) and Eng. shore. Alexander Carmichael (CG II, 342) lists teor and teorr ‘mark, stamp, impress; the mark of the sea upon the shore; the refuse left by the tide upon the beach’ – the former is spelt teòr by Angus Matheson in CG VI, 266: ‘some of these words at least = tiurr [sic]’.
The above forms (A–D) and their senses suggest a derivation from MScots s(c)hor(e), s(c)hoir (Scots shore [ʃoːr]) ‘shore’), probably specifically in the sense ‘land bordering the sea above the high-water mark’. MScots s(c)hor(e) might be expected to yield SG *seòr, *seòrr in the first instance, 
Cf. SG seòrach, besides deòrach, ‘pitiable creature (perhaps a creature picked up on the shore)’ (McDonald 1972, South Uist), but cf. SG deòradh ‘alien, stranger; helpless, afflicted, forlorn being etc.’ (Dwelly 1911).
hence teòr, teòrr (D) via back-formation, and, with o ~ u alternation in Gaelic, *siùrr (siùrra) and tiùr(r) (tiùrra), along with disyllabic tiubha(i)r.
For the disyllabification in tiubha(i)r, cf. Oftedal 1956, 134–35, and Watson 1999, 350–51.
While the original sense of the Gaelic word may have been ‘shore, beach above the high-water mark’, extended senses include ‘high-water mark, mark’, ‘exposed beach, strand’, ‘pile of sand or seaweed at high-water mark, pile’; cf. also the denominative verb tiùrr ‘to heap, pile up’ and the verbal noun tiùrradh. Fr Allan McDonald’s editor John Lorne Campbell notes (McDonald 1972, s.v. teòir) a suggestion that teòir (C) is the genitive of tiùr (D) (cf. SG ceòl ‘music’, gen. ciùil), but this seems unlikely: teòir may be simply be the reflex of a later borrowing.