Longman Dictionary

is an advanced learner’s dictionary, providing definitions by using a restricted vocabulary, helping non-native English speakers to understand meanings easily.

What is academic word?

The Academic Word List was developed by Averil Coxhead at the School of Linguistics and Applied Language Studies at Victoria University of Wellington, New Zealand. The list contains 570 semantic fields which were selected because they appear with great frequency in a broad range of academic texts.

My experience..

I highly recommend it and use it is easy and beautiful and not complicated

Sources..

https://www.examenglish.com/vocabulary/academic_wordlist.html

https://en.m.wikipedia.org/wiki/Longman_Dictionary_of_Contemporary_English