Censorship is any suppression or alteration of speech. Total censorship can only be achieved by double tapping you to the back of the head, and upon reflection you should grasp that censorship is commonly a matter of degree, and prevention of speech at all is almost always unrealistic.

You can ascertain the actual definition of censorship and observe that downvotes are in fact censorship by searching up any authoritative source of your choice and reading the definition provided.