no spring chicken

no spring chicken
(no longer a young person) — уже не ребенок; уже не первой молодости

Example: Sally's no spring chicken, but she plays a fine game of tennis.

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This unflattering expression, often applied to women, has been used since the early 1700s, although spring was omitted from the earliest citation (1711).(Answers.com)

Related vocabulary:
[long in the tooth]
[over the hill]
no longer in the first flush of youth AND
not in the first flush of youth

Example: Though no longer in the first flush of youth she's still remarkably energetic.