Equals NOT Filter in Kibana Visualisation

Hope this will be a quick one:
I try to set a filter in my dashboards which EXCLUDES a certain hostname.
Kibana tells me i can use : to equal a value and :* to search for an exisitin field and also the typical and & or commands. But there is no explanation about NOT equal or NOT existing..
Thanks for any help!

Solved it:
NOT example_field : "sample_value"