A period of time that denotes a long while has elapsed.

A period 28 days long. Every four years, a coon's age is 29 days long.

A word used when describing an unspecific length of time.

Generally used instead of:
"It's been a long time"
"I haven't been here in a while"

A long time.

hickbilly slang used to descibe a long period of time; roughly 8 and a half years

a very long time

Normally raccoons normally live roughly 5-6 years in the wild. However once in awhile you will find a big grizzly one that is about 15-16 years old. This my friends, is what you call a "coon's age".