0 it is not important what is; it makes no difference what (is): --
1 anything or everything: --
I eat whatever I want and I still don't seem to put on weight.
"What can we do tonight?" "It's up to you - whatever you want."
Don't, whatever you do, tell Patrick (= you certainly should not tell him).
"So, I'll bring red wine." "Sure, whatever (= bring that or anything else)."
Apparently he "discovered himself" in India, whatever that means (= I do not know what that means).
2 used instead of the word "what" to add emphasis to a phrase, usually expressing surprise: --
3 → whatsoever : --
4 something that is said to show that you do not respect or care about what someone is saying, especially someone who is asking you to agree with them or agree to do something: --
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.
We kunnen het stap voor stap voltooien, hoe lang de weg ook is en het kan niet worden voltooid, hoe kort de weg ook is, als je niet eens je voetafdruk markeert.