Using The Dictionary On Your Kobo Ereader; Adding Or Removing Dictionaries - Kobo Aura One User Manual

Using the dictionary on your Kobo eReader

If you see an unfamiliar word while you're reading, you can
use your eReader's built-in dictionary to view its definition.
1. While reading, press and hold the word you'd like to
look up.
An underline will appear beneath the word.
2. Lift your finger from the screen.
The word's definition will appear.
The dictionary may not work in some books such as PDFs,
books you borrowed from a public library, or free books you
found on the internet.
Tap the screen to dismiss the dictionary.

Adding or removing dictionaries

You can remove the dictionaries that are installed on your
eReader to save storage space, or add dictionaries in other
languages.
1. Go to your Home screen.
2. Tap the
The Quick Settings panel will appear.
More icon at the top of the screen.