v1.0
Published 01/10/24
steàrnal m. [ˈʃtʲɑːɳɑɫ̪], gen. steàrnail -[al], ‘common tern, Sterna hirundo’ has a number of forms in Scottish Gaelic, often with a following qualifying specific (genitive) noun or adjective (for Irish forms, see A 1(iii), A 3 and A 4(ii), below): 
Reference is to the common tern, unless otherwise indicated.
A. SG steàrnal, stèirneal
(Found in Tiree, Coll, Islay, Argyll and Kintyre.)
A 1. SG steàrnal [ˈʃtʲɑːɳɑɫ̪]
(i) steàrnal (HSS 1828: bittern, lesser tern; MacLeod and Dewar 1839: idem; MacBain 1911: bittern, seabird; Dwelly 1911: arctic tern, bittern; Faclan bhon t-Sluagh˄: [ʃtʹʃɑ:ɾnʹɑl] [?], Islay; ibid.: [ʃtʹɛ:ʴṉʹɑɫ], Coll; AFB˄: /ʃdʲaːRNəL/, Tiree, Coll, Islay, Argyll, Kintyre); in open compounds: (with beag adj. ‘small’) steàrnal beag (Dwelly 1911: lesser tern), steàrnal-beag (AFB˄: idem), (with dubh adj. ‘black’) steàrnal dubh (Dwelly 1911: black tern), steàrnal-dubh (AFB˄: idem);
(ii) stearnal (Shaw 1780: bittern; Mac Farlan 1795: idem; MacFarlane 1815: idem; Armstrong 1825: bittern, lesser tern; Fergusson 1886, 88: arctic tern; Forbes 1905, 37: lesser tern, 245: bittern, 340: tern; Henderson 1910, 127; Faclan bhon t-Sluagh˄: Argyll, Tiree), without lengthmark; in open compounds: stearnal beag (Fergusson 1886, 88: lesser tern), stearnal-dubh (ibid.: black tern);
(iii) cf. Ir. stearnal (O’Reilly 1817 and 1864: bittern; Dinneen 1947: bittern, tern), probably adopted from Shaw’s (1780) Scottish Gaelic dictionary, but see A 4(ii);
(iv) steàrnall (Dwelly 1911: ‘see corra-ghràin [“heron”, ?leg. corra-ghrian “bittern”]’; MacLennan 1925: seabird, bittern);
(v) stearnall (McAlpine 1832: [styârn’´nall]; Fergusson 1886, 68: bittern; Forbes 1905, 337), without lengthmark; misspelt stearneall (MacDomhnuill 1741, 76: bittern), unless *steàirneall was intended, cf. A 2.
A 2. SG stèirneal [ˈʃtʲɛːɳʲɑɫ̪], steàirneal [ˈʃtʲɑːɳʲɑɫ̪]
With a palatal medial consonant cluster:
(i) stèirneal (Faclan bhon t-Sluagh˄: [ʃtʹɛ:rnʹɑɫ], Tiree; AFB˄: /ʃdʲɛːRNʲəL/);
(ii) steirneal (Forbes 1905, 37: lesser tern, bittern, 245: bittern, 337: tern; Dwelly 1911), without lengthmark; in open compounds: (with MacDhùghaill, Eng. M(a)cDougall) steirneal-mhic-Dhughail (Forbes 1905, 37: lesser tern, bittern), steirneal-Mhic-Dhughail (ibid., 330), ?cf. the roseate tern, Sterna dougallii, named after the collector Peter McDougall (1777–1814).
(iii) steàirneal (CG VI, 132: tern, arctic tern).
A 3. Cf. Ir. stearnálach
With the suffix -ach:
stearnálach (Dinneen 1947: Antrim).
A 4. SG stàirneal [ˈʃtɑːɳʲɑɫ̪]
With a non-palatal initial cluster:
(i) stàirneal (MacilleBhàin 1881, 255: Easdale; Dwelly 1911);
(ii) cf. Ir. stairneail (Holmer 1942, 237, s.v. stearnal: [starn´əl], Rathlin).
B. SG steàrnan, stèirnean
(Found in South and North Uist, Harris, Raasay, Argyll, Gairloch.)
B 1. SG steàrnan [ˈʃtʲɑːɳan]
(i) steàrnan (Dwelly 1911; Cunningham 1990, 130; An Stòr-Dàta 1993, s.v. tern; Garvie 1999, 62: tern, arctic tern; Faclan bhon t-Sluagh˄: Harris, [ʃtʹɛ:rnʹɛ̃nʹ], North Uist, [ʃtʹɑ:ʴṉɛ̃ṉ], Raasay; AFB˄: /ʃdʲaːRNan/, Argyll, Raasay, South Uist, Harris); spelt steàrnán in Wentworth 2003, s.v. tern; in open compounds: steàrnan beag ‘little tern’, steàrnan dubh ‘black tern’, (with mòr adj. ‘large’) steàrnan mòr ‘Sandwich tern’ (Garvie 1999, 62);
(ii) stearnan (Fergusson 1886, 88; Forbes 1905, 37: lesser tern, bittern, 340: tern; Faclan bhon t-Sluagh˄: Harris), without lengthmark;
(iii) stearnain (Faclan bhon t-Sluagh˄: little tern, South Uist), with a palatal final consonant.
B 2. SG stèirnean [ˈʃtʲɛːɳʲan], steàirnean [ˈʃtʲɑːɳʲan]
With a palatal medial consonant cluster:
(i) siteirnin (Forbes 1905, 36, 245: bittern), a typesetting error for steirnean (i.e. stèirnean) or steirnein (i.e.stèirnein);
(ii) steàirnean (CG VI, 132: tern, arctic tern).
C. SG steàrdan, steàirdean, steàrdal
(Found in Skye.)
C 1. SG steàrdan [ˈʃtʲɑːɖ̥an]
(i) steardan (Forbes 1905, 37: lesser tern, bittern, 340: tern), without lengthmark; in open compounds: steardan-dubh (ibid., 37: black tern);
(ii) steàrtan (CG VI, 132: tern, arctic tern), with a voiceless medial consonant cluster.
C 2. SG steàirdean [ˈʃtʲɑːɖ̥ʲan]
With a palatal medial consonant cluster:
(i) steàirdean (AFB˄: /ʃdʲaːRdʲan/, Skye);
(ii) steairdean (Dwelly 1911; An Stòr-Dàta 1993, s.v. tern), without lengthmark; spelt steàirrdean in Faclan bhon t-Sluagh˄: [ʃtʹɑ:ʴdʹɑṉ], Skye);
(iii) steàirtean (CG VI, 132: tern, arctic tern), with a voiceless medial consonant cluster.
C 3. SG steàrdal [ˈʃtʲɑːɖ̥ɑɫ̪]
steàrdal (Dwelly 1911), with the final consonant conforming to steàrnal (A 1.).
D. SG steàrnag [ˈʃtʲɑːɳaɡ̊]
(Found in Scalpay, Taransay, Lewis, Ross-shire, Sutherland, also Islay.)
(i) steàrnag (Dwelly 1911: Sutherland; MacLennan 1925; Cunningham 1990, 130; Stewart 2004, 415; Faclan bhon t-Sluagh˄: [ʃtʹɑ:ʴṉɑɡ], Ross-shire, [idem], Lewis, also misspelt stearnàg ‘tern, or chirpish sharp movement, or ternish female’, Scalpay; AFB˄: /ʃdʲaːRNag/, Lewis, Scalpay, Harris, Ross-shire, also Islay); in open compounds: (with bàrr-ghob buidhe m. ‘yellow beak-tip’) steàrnag a’ bhàrr-ghuib bhuidhe ‘Sandwich tern’, (with earball m. ‘tail’) stèarnag an earbaill ‘arctic tern’, stèarnag-bheag ‘little tern’, (with coitcheann adj. ‘general’) steàrnag-choitcheann ‘common tern’, steàrnag-dhubh ‘black tern’, steàrnag-mhòr ‘Sandwich tern’ (AFB˄);
(ii) stearnag (Mackay 1897, 93: Sutherland; Henderson 1910, 127; Christiansen 1938, 4, 16, Lewis; Faclan bhon t-Sluagh˄: Scalpay, Taransay.
While Mackay (ibid.: stearnag) derives this word from Ice. therna ‘tern’ (leg. þerna), Henderson (ibid.: stearnal, stearnag), Christiansen (ibid.: stearnag) and Stewart (ibid.: steàrnag) derive it from ON þerna f. ‘idem’, which McDonald (2009, 428; 2015, 131) considers likely. On the other hand, MacLennan (1925: steàrnag, so also Ó Muirithe 2010) derives it from OEng. stearn, stern ‘idem’, cf. Fris. stern, steern ‘idem’.
In support of the development of ON þerna to SG steàrnal etc., Henderson compares SG stàirsneach ‘threshold’ < EG tairsech; stalc ‘to stiffen’, stalcanta ‘firm, strong’, cf. tailce ‘strength’; SG stàirn ‘noise’, from the same root as tàirneanach ‘thunder’; SG stairirich ‘rumbling’, cf. dairireach ‘rattling noise’; and SG stair, starran ‘stepping-stones’, with a root in OG tar ‘over, across’. (For further discussion and further examples of prothetic s- in the Gaelic languages, see O’Rahilly 1927, 24–29: 27–29; Risk 1970, 628; Gleasure 1973, 190–91; Clancy 1992.)
Nevertheless, Lockwood (≈1976, 273–75) finds Henderson’s thesis unacceptable, arguing that each example must be taken on its own merits and that there is no regular interchange between st- and t- in Gaelic. While OEng. stearn certainly referred to a marine species, Lockwood notes that it ‘is also glossed Lat. sturnus ‘starling’, indicating an association with OEng. stær > Eng. dial. stare, also contained in Eng. starling, an association apparently continued in Eng. dial. starnel “idem”’, 
Dinneen (1947) derives Ir. (Antrim) stearnálach (A 3) from Eng. starnel. Eng. starnel is thought to be a metathesised form of starlin(g) (OED˄); Scots starnal ‘tern’, on the other hand, is derived from SG steàrnal (SND˄). In spite of the apparent parallel in the development of SG mèirlin ‘merlin’ from Scots merlin(g), a derivation of SG steàrnal from Scots starlin, stirlin ‘starling’ seems unlikely because of the semantic disparity.
adding that ‘the name is absent from Middle English, but reappears in a latinised sterna in 1544 (OED˄, s.v. stern)’ and that the ‘only subsequent occurrence is Eng. dial. starn “black tern” 
In Newton (≈1896, 955 fn 2): ‘Starn was used in Norfolk in the middle of this century for the bird known by the book-name of black tern, thus confirming Turner, who, in 1544, described (sub cap. “de Gavia”) that species as “nostrati lingua sterna appellata”. In at least one instance the word has been confounded with one of the old forms of the modern starling. To Turner’s name, repeated by Gesner and other authors, we owe the introduction by Linnæus of Sterna into scientific nomenclature.’
’. Lockwood concludes that ‘the English word is not only poorly attested, it is plainly very local, in fact only one out of a score of tern names found in English dialects and with no indication that it was ever used in the north’, and asks whether it is conceivable that Scottish Gaelic ‘could have borrowed from such a minor and inaccessible source’, suggesting as an alternative that SG steàrnal etc. are likely to be Gaelic echoic terms.
Whether or not under the influence of Scots tern, SG steàrnal may be a by-form of stàirneal ‘noise-maker’, itself a derivative of SG stàirn ‘noise’.
For the suffix, cf. SG deannal ‘conflict, haste’ (deann) and seirgeal ‘emaciated person’ (searg).
SG steàrnal is given as ‘bittern, Botauraus stellaris’ by lexicographers from 1741 up to 1815, ‘bittern and lesser tern’ in 1825, simply ‘tern’ in 1832 – the bittern had become extinct in Scotland during the 18th century (Darling and Boyd 1969, 64) – after which the sense ‘bittern’ is cited by some lexicographers and ornithologists, but ‘tern’ is more usual.
The male bittern makes a far-reaching, booming sound in spring (RSPB˄), while the tern is often noisy in company (RSPB˄).
The form steàrnal persists in Argyllshire (chiefly mainland Argyll, Islay, Coll, Tiree), although a trace of the original stàirneal survives (Easdale and Rathlin). Further north, however, alternative suffixes are used: in steàrnan (chiefly Harris, North and South Uist, Raasay) and steàrnag (chiefly Taransay, Scalpay, Lewis, Sutherland), while steàrdan, with differentiation, is found in Skye.