Use Definer with PDFs and EPUBs
Using translation and dictionary extensions with PDFs can be tricky since most PDF readers don't play well with browser extensions. You may be able to select text, but Definer's popup won't necessarily appear as it does on a webpage.
Fortunately, Definer has its own Reader for this. You can look up words directly in your book without copying them into another tab. It also supports EPUBs and keeps your books in a library, so you can continue where you left off.
If you'd rather keep using your usual PDF viewer, Definer Desktop works with any app. It recognizes text on your screen, so you can look up words in scanned PDFs too, even when the text can't be selected.
Definer's built-in Reader
To open your first book:
- Select Definer's icon in your browser toolbar to open the Extension Window.
- Select Reader in the header.
- Select Choose files and choose a PDF or EPUB from your computer.
The book opens and is added to your library. You can also drag files onto the dropzone. If you choose several files, Reader adds them all and opens the first one.
While reading, the file-with-an-up-arrow Open file button on the document toolbar lets you add another book. Dropping files onto an open document works too.
Open a book from a web address
If your book is online, paste its direct PDF or EPUB address into the library's URL field. The book opens automatically once you finish typing. Press Enter to open it immediately.
If the address doesn't open, download the file from the website and add it with Choose files instead.
Open the PDF you're already viewing
When a PDF is open in a browser tab, select Definer's toolbar icon, then Reader in the Extension Window header. This opens the current PDF in Definer's Reader. For a local file in Firefox, use Choose files or the dropzone instead.
In Chromium browsers, you can also select Make this my default PDF viewer in the library. Later PDFs will open in Reader automatically. Clear the checkbox if you want to go back to your browser's usual PDF viewer.
Look up words while reading
Once your book is open, you can use the Bubble the way you do on websites. Select a word or passage and use your usual activation trigger. If a small circle icon appears beside the selection, select it to open the full Bubble.
Your enabled sources are available here too, so you can check a definition, translate a passage, or listen to pronunciation without leaving the book.
Continue where you left off
You only need to add a book once. Close Reader with the book open, and the next time you open Reader, it returns to where you stopped. For PDFs, this includes your position on the page and zoom. For EPUBs, it remembers your place in the text and text size.
To choose another book, return to the library:
- PDF: open the three-line Tools menu at the right end of the document toolbar, then select Back to library.
- EPUB: select the back-arrow Back to library button beside Open file.
Your most recently read books appear first. Use Search your library to find a filename, then select Continue reading on its card. If you close Reader while the library is showing, that's where it opens next time.
Make more room for the book
If you want more space for the document, use the chevron near the right end of its toolbar to hide the top bar with the filename. Its tooltip changes between Show header and Hide header, and Reader remembers your choice. When the top bar is visible, its Library button gives you another way back to your books.
Top bar visible.
Top bar hidden.
In Definer Desktop, the top bar stays visible because it also contains the window controls.
Read and annotate PDFs
Use the page-number field and page arrows to move through a PDF. The minus and plus buttons adjust the zoom. Page Fit shows the whole page, while Page Width fits it to the width of the reading area.
For longer documents, open the sidebar with the icon at the left end of the toolbar. You can jump to a page from its thumbnail or use the outline if the PDF includes chapter headings or bookmarks. The magnifying-glass Find button searches the document's text.
To mark something you want to return to, use the Highlight, Text, or Draw tools. The marker highlights text, Text adds a note on the page, and the pen lets you draw. If a tool isn't visible, look in the Tools menu.
Your edits are saved automatically to the library copy. Saved to library confirms they're saved. If saving fails, keep the PDF open and select Save now to retry.
To keep a separate copy with your annotations, select the downward-arrow Save button on the PDF toolbar. This downloads the edited PDF without overwriting the original file on your computer.
Your books and annotations stay in the browser or Desktop app where you added them. Keep your original files and download annotated copies before clearing the app's saved data. To remove a book from the library, select its trash icon and confirm with Remove. This removes its reading progress and annotations too; your original file stays untouched.
Read EPUBs
EPUB text adjusts to fit the reading area. Use the small A button to make it smaller or the large A to make it larger. Reader keeps your text size when you return to the book.
The Chapters list lets you jump to a chapter. Use the page arrows, Left Arrow, or Right Arrow to turn pages. The percentage on the toolbar shows how far you've read.
EPUB pages use a dark background with a dark Definer theme and a white background with a light theme. The library and reading toolbars keep Definer's default dark colors. You can change your theme in Definer Options.
Use your browser's PDF viewer
If you'd rather keep using your browser's built-in PDF viewer, Definer offers another option in Chromium browsers such as Chrome and Edge. Only right-click menu activation works here, so double-click and other Bubble triggers won't work as they do in Definer's Reader.
To use it:
- Select text in the PDF.
- Right-click the selection and choose Define followed by the selected text.
A floating lookup window appears, which you can move around while reading.
Watch a quick demonstration: