What is the single word for "circular reasoning"?

Question

Circular reasoning, also known as "begging the question" or "petitio principii," is a logical fallacy that involves assuming that the conclusion of an argument is true in order to support the claim. When someone says, "That action wouldn't be illegal if it weren't prohibited by the law," he or she is committing circular reasoning. What I'm asking is about the single word that means almost the same thing. If a person says, "What is a lyric poem," and someone else responds, "It's a poem that's lyrical," there is a word which describes that type of fallacy. Can anyone tell me what is that word? Thanks in advance!

Answer 1

tautology.  

Answer 2

tautological or tautology  

Answer 3

I'm not sure if this is right, but the question reminds me of Ouroboros or Oroboros, the snake or serpent eating its own tail.