But that's not the only definition. wikipedia defines censorship thus:
"Censorship is the suppression of speech, public communication, or other information. This may be done on the basis that such material is considered objectionable, harmful, sensitive, or "inconvenient".[2][3][4] Censorship can be conducted by governments,[5] private institutions, and other controlling bodies. " (https://en.wikipedia.org/wiki/Censorship)
You can argue whether or not moderation is necessary or not but it most definately is censorship.
The way it is being applied by FB is most certainly censorship and highly inappropriate and destructive.