portable electronic dictionary; pocket electronic dictionary; PED
Refers to a dedicated handheld device for looking up words, common among students before smartphones became widespread.
When I was a high school student, I got an electronic dictionary.
digital dictionary; electronic dictionary (app or website)
Covers dictionary software, smartphone apps, and online dictionary services, not just physical devices.
I looked up the word using a digital dictionary app on my smartphone.
I looked up the word I didn't know in the electronic dictionary.
You may use an electronic dictionary during class.
Since I'm studying abroad, I plan to bring an electronic dictionary.