I actively use online dictionaries in my studies and at work. I am excited to share some links to professional terminology dictionaries with you that I have encountered online.
What to start from
Accounting & finance
Compilation by Jukka Melaranta
Other dictionaries
Other compilations of links
MOT Dictonary
If you are a student in the Finnish institution, most likely you have an access to MOT Dictionaries. I really recommend using them!
For the linguistic dessert
P.S. If any of the links is not working anymore, try a Wayback Machine.