Samsung Galaxy A8 User Manual page 46

Basics
Dictionary
Look up definitions for words while using certain features, such as when browsing webpages.
1
Tap and hold over a word that you want to look up.
If the word you want to look up is not selected, drag
2
Tap More → Dictionary on the options list.
If a dictionary is not preinstalled on the device, tap Move to Manage dictionaries →
next to a dictionary to download it.
3
View the definition in the dictionary pop-up window.
To switch to the full screen view, tap
definitions. In the detailed view, tap
Search Web to use the word as a search term.
or
. Tap the definition on the screen to view more
to add the word to your favourite words list or tap
46
to select the desired text.