Sixth \Sixth\, n.

1. The quotient of a unit divided by six; one of six equal parts which form a whole.

2. The next in order after the fifth.

3. (Mus.) The interval embracing six diatonic degrees of the scale.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Sixth \Sixth\, a. [From Six: cf. AS. sixta, siexta.]

1. First after the fifth; next in order after the fifth.

2. Constituting or being one of six equal parts into which anything is divided.

Source: Webster's Revised Unabridged Dictionary (1913)