The Latin expression ex-libris is formed by the preposition ex indicating origin or provenance and the plural ablative of liber, meaning book. Its meaning would be equal to "Among the books of...", "Of the books of...", "Book of..." or "Book belonging to...". The Latin locution, as you can see, allows us to express in a single word a concept that in our language would need several words.
Are there other words for exlibris?
Ex libris, Ex Libris, Exlibris, Ex-Libris or Ex-libris?
One day a retired Latin professor came to my booth and told me that I misspelled the term "ex-libris", that Latin has never been hyphenated, and that he would like his to have only a separation between ex and libris. I told him that I had always seen it written that way, but that I would do his as he had asked. Over the years I did some research on the subject and came across this. In 1903 the Iberian Magazine initiated a survey to find out how the word ex libris should be written, among all its variants: "Ex libris", "Ex Libris", "Exlibris" or "Ex-libris". Finally it was agreed to do it with a hyphen between ex and libris. But be careful if someday you have to write ex librismo (a word used to talk about ex-libris collecting or the study of the production technique of ex-libris) or ex librista (a person who designs ex-libris, has ex-libris or collects them) remember these two words are hyphenated.
I hope that with this post you have solved all your doubts about the word ex-libris and its variants. In any case, what is clear is that with your own ex-libris you will be able to lend any volume of your collection without fear of losing it.