- sixth [siksth]adj.[ME sixth < OE sixta, akin to Ger sechste, L sextus: see SIX & -TH2]1. preceded by five others in a series; 6th2. designating any of the six equal parts of somethingn.1. the one following the fifth2. any of the six equal parts of something; 1/ 63. Musica) the sixth tone of an ascending diatonic scale, or a tone five degrees above or below any given tone in such a scale; submediant; superdominantb) the interval between two such tones, or a combination of themc) the chord formed by a triad in which the fundamental tone is raised an octave, creating a new interval of a sixth, as E-G-C: in full sixth chordadv.in the sixth place, rank, group, etc.sixthlyadv.
English World dictionary. V. Neufeldt. 2014.