I am not sure what you mean by definition but if something is raised to a negative power than write it as a fraction, swap it to the other side of the fraction line and change the negative to a positive.
eg
$$6x^{-3}=\frac{6x^{-3}}{1}=\frac{6}{1\times x^{+3}}=\frac{6}{x^{3}}$$
Does that make sense? (Only the x was raised to a negative power so everthing else stayed in its original position.)
I am not sure what you mean by definition but if something is raised to a negative power than write it as a fraction, swap it to the other side of the fraction line and change the negative to a positive.
eg
$$6x^{-3}=\frac{6x^{-3}}{1}=\frac{6}{1\times x^{+3}}=\frac{6}{x^{3}}$$
Does that make sense? (Only the x was raised to a negative power so everthing else stayed in its original position.)