1) Coeval 2) Contemporaneous 3) Of the same age or duration 4) Of the same period 5) Synchronal 6) Synchronic 7) Synchronous 1) Coeval 2) Synchronal 3) Synchronic 4) Synchronous 
of the same age; coeval
• (a.) Of the same age; beginning to exist at the same time; contemporaneous.
Co`e·ta'ne·ous adjective [ Latin coaetaneus ; co- + aetas age.] Of the same age; beginning to exist at the same time; contemporaneous. -- Co`e*ta'ne*ous*ly , adverb « And all [ members of the body] are coetaneous . Bentley.
[adj] - of the same period
coetaneous Of equal age, duration, or period; coeval.
coeval adjective of the same period
of the same age or duration.