ne'o VUhU3 cmavo

unary mathematical operator: factorial; a!.

On affix form:

cnebo
x1 is a/the neck [body-part] of x2; [metaphor: a relatively narrow point].

In notes:

fampi'i
x1 is the factorial of x2.
ma'oi'e
Like "ma'oi" but outputs the officially-designated/canonical sub-selma'o (if any) to which the immediately following and quoted word (cmavo) belongs, otherwise outputting the whole relevant selma'o in fashion equivalent to "ma'oi".
ne'o'a
mekso ternary operator: the generalized incomplete (factorial-extending) Pi function; for input (X1, X this word outputs the definite integral of t^X1 e^-t with respect to t from X2 to X3 (see notes for default values).
ne'o'au
mekso quaternary operator: polygamma function; for input X1, X, outputs the (-X2)th derivative of Log(ne'o'a(X1, X)) with respect to X1.
ne'o'o
mekso quaternary operator – Pochhammer symbol: with/for input (X1, X, this word/function outputs \prodk = 0^X2 - 1 (X; by default, X4 = 1 unless explicitly defined otherwise.