Alpha Puzzle

What makes the following phrase unique? “No hi-def.”

If you google "No hi-def" you get a lot of different responses. So it can't be unique.

"N-O," "H-I" and "D-E-F" can all be found in order inside the alphabet. They're the only "words" for which this is true.

It's easy to come up with non-words, such as "def" that are alphabetically sequential.

An abdominal muscles is often referred to as an "ab".
Without "De" Robert Niro may not be as well known.
Stu is a common nickname for someone named Stewart.
Hij is the name of a river.

And when you get into foreign words, it is more common.

Clever observation on your part, however.