If you like reading nice expositions to mathematical terminologies, then I would suggest you to consider following two websites:
- Armin Straub’s index to “What Is…?” column in the Notices of the AMS: http://arminstraub.com/math/what-is-column
- Joseph Nebus’s “A-To-Z” series:
- Summer 2017: https://nebusresearch.wordpress.com/2017/09/29/the-summer-2017-mathematics-a-to-z-what-i-talked-about/
- End 2016: https://nebusresearch.wordpress.com/2017/01/03/the-end-2016-mathematics-a-to-z-roundup/
- Leap Day 2016: https://nebusresearch.wordpress.com/2016/04/29/a-leap-day-2016-mathematics-a-to-z-the-roundup/
- Summer 2015: https://nebusresearch.wordpress.com/2015/07/24/a-summer-2015-mathematics-a-to-z-roundup/