
das Geheimnis
secret
Information that is not generally known or not meant to be known and is entrusted to only a few people.
Er hat mir unter vier Augen ein Geheimnis anvertraut.
He confided a secret to me in private.
secret
Loading your saved state.

secret
Information that is not generally known or not meant to be known and is entrusted to only a few people.
Er hat mir unter vier Augen ein Geheimnis anvertraut.
He confided a secret to me in private.

secret
The hidden cause or decisive factor behind something, often behind a success or a phenomenon.
Das Geheimnis eines guten Kuchens liegt in den frischen Zutaten.
The secret of a good cake lies in the fresh ingredients.
The word 'Geheimnis' (secret) is related to 'heimlich' (secretly). The root 'heim' means 'home' or 'private'. So a 'Geheimnis' is something that you keep private, hidden away.
Sie erzählte mir heimlich von ihrem Plan.
She secretly told me about her plan.
When it is about information between people, the first meaning is intended. When it is about the cause of a success or a phenomenon (often with the genitive, as in 'das Geheimnis des Erfolgs' — the secret of success), the second meaning is intended.
Kannst du ein Geheimnis für dich behalten?
Can you keep a secret?
Certain verbs are often used with 'Geheimnis' (secret): you can 'bewahren' (keep), 'hüten' (guard), 'für sich behalten' (keep to yourself), 'verraten' (reveal), or 'lüften' (uncover) a secret.
Er hat aus Versehen das Geheimnis verraten.
He accidentally revealed the secret.
The expression 'ein Geheimnis aus etwas machen' means that someone does not want to speak openly about something, even though it may not be necessary to be secretive.
Warum machst du so ein Geheimnis aus deinem neuen Job?
Why are you making such a secret of your new job?
In this meaning, 'Geheimnis' (secret) often appears with a genitive or a 'von' construction to say what it is the secret of: 'das Geheimnis des Lebens' (the secret of life) or 'das Geheimnis von gutem Wein' (the secret of good wine).
Er versucht, das Geheimnis des Glücks zu finden.
He is trying to find the secret of happiness.
key / wrench
Der Schlüssel is the decisive means that leads to a result or makes a solution possible. Das Geheimnis is a decisive factor that is initially hidden or not generally known. Schlüssel fits a clear path to success, while Geheimnis fits a surprising hidden cause.

Eine bisher unbekannte Trainingsmethode war das Geheimnis ihres Erfolgs.
A previously unknown training method was the secret to her success.
Regelmäßiges Üben war der Schlüssel zu ihrem Erfolg.
Regular practice was the key to her success.