third third estate the common people as part of a country's political system. The first two estates were formerly represented by the clergy, and the barons and knights; later the Lords spiritual and the Lords temporal.
third eye in Hinduism and Buddhism, the ‘eye of insight’ in the forehead of an image of a deity, especially the god Shiva.
third man an unidentified third participant in a crime; the phrase in this sense derives from the screenplay (1949) by Graham Greene, later filmed by Carol Reed, in which the plot centres on the doings of this shadowy figure. After the flight in 1951 of the Soviet agents Guy Burgess and Donald Maclean to Moscow, the phrase was used in connection with the third party (later demonstrated to be Kim Philby) who was thought to have warned them.
The 3rd of May an informal name for Goya's picture ‘The 3rd of May 1808: The Execution of the Defenders of Madrid’, painted to commemorate the execution by the French of Spanish insurgents against the invading Napoleonic forces; it later influenced Manet's depiction of the execution of the Emperor Maximilian of Mexico (1832–67).
Third Order an order for lay members retaining the secular life and not subject to the strict rule of the regular orders, originated by St Francis of Assisi and now established among Franciscans, Dominicans, and others.
third rail in the US, a subject, especially Social Security, considered by politicians too dangerous to modify or discuss; literally, an additional rail supplying electric current as used in some electric railway systems.
Third Reich the Nazi regime, 1933–45, considered as succeeding the Holy Roman Empire (962–1806) and the German Empire (1871–1918) as the previous periods of empire (see Reich). The name, which is a translation of German drittes Reich, is recorded in English from 1930, in an interview in The Times of 26 September 1930 with Hitler.
third time lucky proverbial saying, mid 19th century, reflecting the idea that three is a lucky number; often used to suggest making another effort after initial failure.
the third time pays for all proverbial saying, late 16th century, meaning that success after initial failure makes up for earlier disappointment; it may also reflect the idea that a third affempt is likely to be more fortunate.
third way in politics, a middle way between conventional right- and left-wing ideologies or policies; an ideology founded on political centrism or neutrality. In the 1990s the third way became identified with the political programmes of centre-left parties in Western Europe and North America, characterized by both market-driven economic policy and a concern for social justice; in this context it is conceived of as an alternative to, rather than a compromise between, conventional right- and left-wing ideologies, and in the UK has been particularly associated with the premiership of Tony Blair.
Third World the developing countries of Asia, Africa, and Latin America. The phrase was first applied in the 1950s by French commentators who used tiers monde to distinguish the developing countries from the capitalist and Communist blocs.

third / [unvoicedth]ərd/ • ordinal number constituting number three in a sequence; 3rd: the third century the third of October Edward the Third. ∎  (a third/one third) each of three equal parts into which something is or may be divided: a third of a mile. ∎  the third finisher or position in a race or competition: Hill finished third. ∎  the third in a sequence of a vehicle's gears: he took the corner in third. ∎ Baseball third base. ∎  the third grade of a school. ∎  thirdly (used to introduce a third point or reason): second, they are lightly regulated; and third, they do business with nonresident clients. ∎  Mus. an interval spanning three consecutive notes in a diatonic scale, e.g., C to E (major third, equal to two tones) or A to C (minor third, equal to a tone and a semitone). ∎  Mus. the note that is higher by this interval than the tonic of a diatonic scale or root of a chord. ∎ Brit. a place in the third-highest grade in an examination, esp. that for a degree.PHRASES: third time is a charm (or Brit. third time lucky) used to express the hope that, after twice failing to accomplish something, one may succeed in the third attempt.

third ordinal of the numeral three OE.; sb. third part XIV; musical interval XVI. OE. (late Nhb.) þird(d)a, -e, var. of þridda = OS. thriddio (Du. derde), OHG. dritto (G. dritte), ON. þriði, Goth. þridja :- Gmc. *þriðjaz :- IE. *tritjós (cf. Skr. tṛtī́ya-, Gr. trítos, L. tertius, OSl. tretij, W. trydydd), f. stem of THREE.
Hence thirdly (-LY2) XVI. third-rate XVII. thirteen OE. þrēotīene = OS. thriutein (Du. dertien), OHG. drīzehan (G. dreizehn), ON. þrettán. thirteenth OE. þrēo-, þrīetēoða, ME. þritteþe, þreottenþe (XII), þrittenþe (XIV). þirttenth (XV), thirteenth (XVI); see -TH2. thirty OE. þrītiġ = OS. thrītig (Du. dertig), OHG. drízzug (G. dreissig), ON. þrírtegr, Goth. (acc.) þrins tiguns; see -TY2. thirtieth OE. þrītigoða, þritteogoða.

third (noun). Melodic and harmonic interval, reckoned as taking 3 steps in scale (major or minor) counting bottom and top notes, thus, major third (C up to E) or minor third (C up to E♭) or diminished third (C♯ up to E♭).