adj o,ā. (< ro-rethech?) adj. of uncertain meaning, perh. `running swiftly', hence swift, rapid, impetuous: romechtar cleith curi rith rurt[h]ech aga catha, Corm. Y 1018 p. 88 (orc trēith) = rom-echutar clethi cuire rith rurthig ágae catha, Corm. p. 35 = riuth ruirthech, Bodl. ruirthech rian, RC xx 258 ( ACC 63 Comm. ) = ruthach, LU 857 . tracht ruirthech `strand overrun', RC xxvi 32 § 151 (glossed .i. ro-ḟirthach do longaib, LL). da ndroch . . . ruirthecha, TBC-I¹ 3392 . Of persons swift, prompt (in action or resolve)? fochen Labraid . . . urlam do rath, rurtech do chách, SCC 18 , `munificent', O'Curry, Atlantis i 383.28 . rētglu ruirthech, Bruchst. i § 106 (of an abbot) = rédlu ruirtech, LB 101b = ruireach, AFM i 512 (`ein Stern mächtigen Laufes', Meyer). batar ruirthig bar ríg `Eure Könige waren freigebig', Alex. 193 , cf. 572 . ros fallnatar rigi ruirthechai, 199 (leg. ríga ruirthecha?). intlec[h]t ruirthech, Anecd. v 26.5 (glossed roertach).

As n.l. Ruirthech, older name of the r. Liffey, Metr. Dinds. iii 104.6 .