I heard a radio announcer say that something was “unlike no other.” I could tell from the context that he meant the thing he was talking about was unique.
As I usually do when I read or hear nonstandard usage in a professional context, I jumped on my search engine to see if anyone else was using it. What I found suggests that many speakers use “unlike no other” as if it did mean “one of a kind.”
Relationship problem… unlike no other? (about a boy who feels his romantic situation is unique)
Urban Novel Unlike no Other (reviewer recommending a novel)
Trees unlike no other (description of unusual trees)
A community unlike no other! (a group of gamers)
A show unlike no other (ad for an entertainment program)
The expression “unlike no other” doesn’t mean “one of a kind.” On the contrary, it means “like all others.”
The prefix un- makes a word negative. In English, adding not to a statement that contains an un- word is said to cancel out the un-, resulting in a statement to be taken as a positive. Example: “I am not unhappy.” is equivalent to “I am happy.”
Note: A discussion of the “two negatives equal a positive” rule in English calls for a post of its own. This one focuses on why the expression “unlike no other” should be avoided.
Like means “having the same characteristics as something else.” Adding the prefix un- to like creates an adjective that means “dissimilar.” Technically, to say that something is “unlike no other,” is to say that it is “like everything else.”
To express the thought that something is “unique” or “one of a kind,” drop the un- and say that the thing is “like no other.” For example,
Grab a cup of cider and head to Red Arrow Park in beautiful Milwaukee, Wisconsin for a fun, low-key New Years Eve like no other.
A Race Like No Other: 26.2 Miles Through the Streets of New York (book title)
Another way to express the thought is to use the phrase “not like any other.”
They proof their dough for 24 hours which allows it to rise and ferment to a flavor not like any other bread available in Brooklyn…
This is truly a movie not like any other.
Apparently the wording “unlike no other” sounds pleasing to the ears of many speakers, but it is not standard English.