Question

Why create system call is called creat?

Also, why a define for a buffer size is called BUFSIZ and not BUFSIZE?

Are there any other such examples?

Related: (taken from comments)
What did Ken Thompson mean when he said, “I’d spell create with an ‘e’.”

Answer 1

From LSP (page 28):

Yes, this function’s name is missing an e. Ken Thompson, the creator
of Unix, once joked that the missing letter was his largest regret in
the design of Unix.