Je ne sais quoi is a French phrase that translates to 'I don't know what' and is used to describe an intangible quality or feeling. It is often used to describe someone who has a certain charm or charisma. The four crossword solutions AURA, FACTOR, ELAN, and OOMPH all relate to this concept of je ne sais quoi. An AURA is an invisible field of energy that surrounds a person or object, and can be used to describe a person's presence or charm. A FACTOR is something that contributes to a result, and in this case it could refer to the qualities that make up a person's je ne sais quoi. ELAN is a French word meaning enthusiasm or vigor, and is often used to describe someone with a certain flair or style. Lastly, OOMPH is a slang term for energy, enthusiasm, and charisma, and is often used to describe someone with a strong presence. All of these words relate to the concept of je ne sais quoi, and together they help to describe the intangible quality or feeling that someone may possess.