Posted by Bill Raymond on December 04, 1999
In Reply to: "Five by Five" posted by E. on December 04, 1999
: : Where does the phrase "Five by Five" come from?
: FIVE BY FIVE -- Five-by-five can mean an obese person. But the meaning that's been discussed here at Phrase Finder is from radio communications. Five by five, or "five by," means "I'm hearing you loud and clear." It can also mean, OK or everything's perfect. These definitions are from "The Random House Historical Dictionary of American Slang," Vol. I, A-G, by J.E. Lightner. I've also heard the term used for describing the bed of a pickup truck that's five by five.
I'm an old grey surfer and feel compelled to tell you of my experience in WWII as a ground technician when testing aircraft radios. The standard procedure, to indicate clarity and strength of reception when reception was optimum, was to reply "clear five's". I've never given a thought as to its origins and can't vouch for it's universal usage but we certainly used it in RAF Bomber Command.