Meaning of circumvolution

cir•cum•vo•lu•tion

1. the act of rolling or turning around: planetary circumvolution.
2. a single complete turn or cycle.
3. a winding or folding about something: the circumvolutions of a boa.
4. a fold so wound: the circumvolution of a snail shell.
5. a winding in a sinuous course; a sinuosity: the circumvolutions of the river.
6. a roundabout course or procedure, or an instance of such: The speaker's circumvolutions bored the audience to tears.