Step 1 :The leading term of a polynomial is the term with the highest degree.
Step 2 :In the given function $f(x)=-6 x^{7}+3 x^{2}+18$, the leading term is $-6x^7$.
Step 3 :The degree of a polynomial is the highest power of the variable in the polynomial.
Step 4 :In the given function $f(x)=-6 x^{7}+3 x^{2}+18$, the degree is 7.
Step 5 :The leading coefficient of a polynomial is the coefficient of the leading term.
Step 6 :In the given function $f(x)=-6 x^{7}+3 x^{2}+18$, the leading coefficient is -6.
Step 7 :Final Answer: i. The leading term of $f$ is \(\boxed{-6x^7}\). ii. The degree of $f$ is \(\boxed{7}\). iii. The leading coefficient of $f$ is \(\boxed{-6}\).