Early historical forms of this anglicised place-name such as ‘Torkill’ (2) and ‘Torchill’ (6) clearly do not support derivation from Teamhair (14). Tarahill cannot therefore be identical with the historical toponym ‘Teamhair Brogha Nia’ (15) as suggested by O’Donovan and followed by Hogan (Onomasticon t[eamhair] broga niad).

‘Torkill’ (2) when considered in tandem with ‘Terroghyll’ (3) in -gh- and ‘Torowhill’ (7a) in -h-, rather indicates derivation from Torchoill, a closed compound consisting of tor “tall rock, steep rocky height” (in reference to the conspicuous hill here) and coill “wood”. The presence of ‑ch- and ‑gh- in anglicised forms such as ‘Torchill’ (6) and ‘Terroghyll’ (3) indicate -ch- /x/ in the Irish precursor, and the occurrence of a vowel between ‑r- and ‑gh- in ‘Terroghyll’ (3), etc., reflects the epenthesis expected in the cluster -rch- /rx/ (see Ní Chiosáin, 1997 p.368). A familiar example of this same epenthesis is the surname Ó Murchú, frequently anglicised ‘O’Murogho’ (e.g. CPR p.366). The further development of ‑gh- (< ‑ch-) to ‑h- in anglicisation, e.g. ‘Torohill’ (7b), is also expected (see Kiltillahan/Coill tSeancháin, par. Carnew).

Torc-choill “boar-wood” has been suggested as a possible precursor elsewhere (see BPP p.87). However, this proposed form is not consistent with the survival of a lenited guttural ‑ch- /x/, e.g. ‘Terroghyll’ (3) and ‘Torchill’ (7), which would be expected to be assimilated to the preceding ‑c /k/ of Torc-. Nor would the consonant cluster -rc- /rk/ produce the epenthetic vowel detailed above (see Ní Chiosáin, 1997 p.369).

‘Torchair’ (1) as found in a twelfth-century Irish source appears to refer to this location. If the spelling and identification are accurate, this earlier form may reflect assimilation of final ‑ll with the ‑r- of the preceding syllable (cf. Gardamus, par. Mayglass). The meaning of this Irish form is obscure. [Matters are further complicated by a second early Irish form of the name which has been brought to the attention of the Placenames Branch by the editors of FSÁG, namely ‘Torachail’ (Anecdota ii, 36). This has a final -l and also an extra internal vowel not seen in ‘Torchair’, which is problematic.] Note that the early date of the[se] Irish attestation[s] gives rise to the possibility that [one of these] spelling[s] represents the original form of the name, and that [it subsequently developed to Torchoill due to [...] reinterpretation.

[[Excerpt from Logainmneacha na hÉireann IV: Townland Names of County Wexford, 2016, with additional material in square brackets.]