Angular Momentum: A vector quantity representing the rotational inertia and rotational velocity of an object. Denoted as $L = I \omega$ where $I$ is moment of inertia and $\omega$ is angular velocity.
Torque: A force that causes an object to rotate around an axis. It is given by $\tau = r \times F$, where $r$ is position vector and $F$ is force.
Gyroscope: A device consisting of a wheel or disk mounted so that it can spin rapidly about an axis which is itself free to alter in direction.