1) Convolution 
• (n.) A sinuous depression or sulcus like those separating the convolutions of the brain. • (n.) A state of being anfractuous, or full of windings and turnings; sinuosity.
An·frac`tu·os'i·ty noun ; plural Anfractuosities . [ Confer French anfractuosité .] 1. A state of being anfractuous, or full of windings and turnings; sinuosity. « The anfractuosities of his intellect and temper. Macaulay. » 2. ...
the state or quality of being anfractuous. · a channel, crevice, or passage full of windings and turnings.