adjective

1. preceded by six others in a series; 7th
2. designating any of the seven equal parts of something

Etymology: ME seventhe, a new formation < seoven + -th, replacing OE seofande (akin to Ger siebente) & seofotha

noun

1. the one following the sixth
2. any of the seven equal parts of something;
3. Music
   1. the seventh tone of an ascending diatonic scale, or a tone six degrees above or below any given tone in such a scale; leading tone; subtonic
   2. the interval between two such tones, or a combination of them
   3. the chord formed by any tone and the third, fifth, and seventh of which it is the fundamental
      in full seventh chord

adverb