O.E. metathesis of
þridda, from P.Gmc.
*thridjas (cf. O.Fris.
thredda, O.S.
thriddio, M.L.G.
drudde, Du.
derde, O.H.G.
dritto, Ger.
dritte, O.N.
þriðe, Goth.
þridja), from PIE
*tritjos (cf. Skt.
trtiyas, Avestan
thritya, Gk.
tritos, L.
tertius, O.C.S.
tretiji, Lith.
trecias, O.Ir.
triss). Related to O.E.
þreo (see
three). Metathesis of
thrid into
third is attested from c.950 in Northumbria, but
thrid was prevalent up to 16c. The noun meaning "third part of anything" is recorded from 1382.
Third rail in electric railway sense is recorded from 1890.
Third World War as a possibility first recorded 1947.
Third-rate "of poor quality" is from 1814, ult. from classification of ships (1649);
third class in railway travel is from 1839.
Third Reich (1930) is a partial transl. of Ger.
drittes Reich (1923).
Third party in law, insurance, etc., is from 1818.