Dictionary:

sexagenarian

  (sĕk'sə-jə-nâr'ē-ən)

A person who is 60 years old or between the ages of 60 and 70.

1. Being 60 years old or between the ages of 60 and 70.
2. Of or relating to a sexagenarian.

[From Latin sexāgēnārius, sexagenary. See sexagenary.]

The noun has one meaning:

Meaning #1: someone whose age is in the sixties

The adjective sexagenarian has one meaning:

Meaning #1: being from 60 to 69 years old