Should I use "oldest friend" or "longest friend"?

"Oldest friend" typically refers to a friend that a person has known for the most amount of time, regardless of how often they may see or communicate with each other. It emphasizes the length of the friendship, and suggests a deeper connection or history.

On the other hand, "longest friend" can also refer to a friend that a person has known for a long time, but it may also imply a more frequent or ongoing relationship. It emphasizes the duration of the friendship, but not necessarily the depth of the connection.

In general, both phrases are interchangeable and can be used depending on the context and personal preference of the speaker. If you want to emphasize the length of the friendship and the deep connection you have with this friend, "oldest friend" might be more appropriate. If you want to emphasize the duration of the friendship and the fact that you still keep in touch and maintain a close relationship, "longest friend" might be a better fit.