n. A person whose age is between thirty and thirty-nine years, inclusive; someone in his or her thirties.
adj. Between 30 and 39 years of age.
adj. Between 30 and 39 in number.
Word Usage
"She had some moments of acting glory -- part of the original cast of the hit musical "The Best Little Whorehouse in Texas," roles in "L.A. Law" and "thirtysomething" -- and then hit a wall."