Help me with the meaning

Fear comes in many forms, and we usually don't call it by its four letter name. Fear itself is quite fear-inducing. Most intelligent people in the world dress it up as something else: optimistic denial.

Can anyone explain me what the sentence "we usually don't call it by its four letter name" mean?

Does it mean when we feel ourself fear of sth. we most likely don't mention it as "fear"?

Thanks in advance.