Difference between “Long John” and “long johns”

Long John—

1. a nickname of a tall, thin man:

• As I had warned Long John, there comes a time when you begin to think that you know it all.

2. is used of a long coffee table:

• Some of his most famous pieces from this period are the 1946 “Long John” table and the simple 1948 chaise lounge.

3. a timber tree (Triplaris surinamensis) found along the lower Amazon and in the Guianas:

• An unusual tree which is flowering at the moment is the Long John tree.

long johns —(sl.) long woolen underwear:

• We stripped down to our long johns so that the technicians could plaster us all over with strips of wet paper.