Longstanding (adjective)

1. Existing for a long time; of long duration.
2. Long established.

Origin:

Early 19th century: from long + standing.

Examples:

1. The company has a longstanding reputation for quality.
2. The conflict is longstanding and has yet to be resolved.
3. The tradition is a longstanding one in the community.
4. The organization has a longstanding policy of non-discrimination.
5. The friendship is a longstanding one between the two.