Webster's Revised Unabridged Dictionary · 1913

Sixth

Sixth , adjective

[From Six: compare Anglo-Saxon 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.

Sixth , noun

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