Mine is “palimpsest”. I first encountered this word while reading The Secret History by Donna Tartt.
Definition: a manuscript or piece of writing material on which the original writing has been effaced to make room for later writing but of which traces remain.
I love that there’s a word for this.
I’m a big fan of portmanteau, not a hard one but a fun one. And in Spanish the word cuaderno always made me happy, it means “notebook.”