signiert
signed
Provided with a signature, usually by the person who created something (e.g., an author, artist, or athlete).
Er besitzt eine vom Autor signierte Erstausgabe des Buches.
He owns a first edition of the book signed by the author.

signed
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signed
Provided with a signature, usually by the person who created something (e.g., an author, artist, or athlete).
Er besitzt eine vom Autor signierte Erstausgabe des Buches.
He owns a first edition of the book signed by the author.

'Signiert' (signed) is the past participle of the verb 'signieren' (to sign). It is very often used like an adjective to describe a noun that bears a signature.
Ich habe ein signiertes Trikot von meinem Lieblingsspieler.
I have a signed jersey from my favorite player.
Besides being used as an adjective, 'signiert' (signed) is also part of the perfect tense or passive voice with the auxiliary verbs 'haben' (to have) or 'werden' (to be/become).
Der Autor hat mein Buch persönlich signiert.
The author personally signed my book.
You can tell from the context whether a real or digital signature is meant. Words like 'Buch' (book), 'Foto' (photo), or 'Künstler' (artist) point to a handwritten signature, while 'Software' (software), 'E-Mail' (email), or 'digital' (digital) refer to a digital signature.
Die E-Mail war digital signiert und daher vertrauenswürdig.
The email was digitally signed and therefore trustworthy.
In the non-digital world, things that have personal or collectible value are often signed, for example a book, a photo, a work of art, or a jersey.
Ein vom Künstler signiertes Gemälde ist oft viel mehr wert.
A painting signed by the artist is often worth much more.
marked / signed / drawn
'gezeichnet' and 'signiert' can both have to do with a signature. In this sense, 'gezeichnet' is very formal and often appears at the end of letters or documents, frequently as 'gez.'. It shows who signed the writing. 'signiert' is used more when an object has been given a signature directly, for example a book, a photo, or a work of art. The words can be confusing because both refer to a signature. Remember: in official letters or documents, you often see 'gezeichnet'; for autographs and works, people usually say 'signiert'.

Sie bewahrt das signierte Buch des Autors in ihrem Regal auf.
She keeps the author's signed book on her shelf.
Unter dem Schreiben stand: gezeichnet, der Geschäftsführer.
At the bottom of the letter it said: signed, the managing director.