The police uncovered no evidence, so the identity of the robbers remained a puzzling enigma.
She was an unusual person, and an enigma to those who tried to understand her.
It is a noun. Example: The enigma of her identity continued to distract him for the rest of the day.
"An enigma wrapped in mystery and riddled with controversy" is how UFO's have been described. He/she is an enigma. The location of 'The Lost Dutchman' gold mine remains an enigma.
The use of the word enigma is apparently an enigma to you! Delicious irony!
Enigma
hard, challenging
Enigma: An seemingly unbreakable code that originated in WWII when the German's used it for communication. It now means just that - a difficult code to decipher or a mystery. "His body language baffled me, I couldn't figure it out - He was a walking enigma."
The word "enigma" is a noun. It refers to something that is mysterious, puzzling, or difficult to understand.
AenigmaNote: Even though the word Enigma is contained within this word, it was originally derived from the greek word ainigma, from ainissesthai which mean speak allusively, and from ainos meaning fable. Originating back from mid-16th Century.Rumor: It is said that a new latin word has been created for brainteasers, a synonym for puzzles, the word is subverticula.P.S. There is no actual Latin word for the English word Puzzle, another equivalency would be the word scirpus.
The mystery surrounding the disappearance of the treasure was an enigma to the entire town.
No
Just because something is difficult to be understood, making it an enigma, that does not necessarily make the thing a negative thing. I have a friend who is an "enigma" to me but he is one of my best friends and a very positive part of my life.