longtime
adj.adj. having been something for a very long time. You use this to describe a person's role, job, or relationship that has lasted many years.
adj. having held a particular status, role, or relationship for an extended duration. Typically used to describe people in professional or personal capacities.
She is a longtime friend of the family.
The company's longtime CEO announced his retirement after thirty years of service.
A longtime advocate for environmental reform, the senator spent her final term drafting legislation to protect the state's remaining wetlands.
From long + time.
Attributive adjective — almost exclusively placed before the noun it modifies.
They have been friends for longtime.They have been longtime friends.Longtime is an adjective that modifies a noun; it cannot be used as a noun phrase after 'for'.