This is the 14711th most frequent German word.
neunjährige
"Neunjährige" means "nine-year-old" in English.
Here, 'neunjährige' is used as an adjective describing the noun 'Mädchen', meaning nine years old.
Das neunjährige Mädchen spielt gerne im Park.
The nine-year-old girl likes to play in the park.
In this sentence, 'neunjährige' functions as an adjective describing the noun 'Vertrag', indicating its duration of nine years.
Der neunjährige Vertrag wurde erfolgreich verlängert.
The nine-year contract was successfully extended.
In this instance, 'neunjährige' is used as an adjective to describe 'Erfahrung', referring to the period of experience.