Sixtieth \Six"ti*eth\, a. [As. sixtiogo[eth]a, sixtigo[eth]a.]1. Next in order after the fifty-ninth.
2. Constituting or being one one of sixty equal parts into which anything is divided.
Source: Webster's Revised Unabridged Dictionary (1913)
Sixtieth \Six"ti*eth\, n.1. The quotient of a unit divided by sixty; one of sixty equal parts forming a whole.
2. The next in order after the fifty-ninth; the tenth after the fiftieth.