Does the boundary between the near (visible) and far sides of an object have a name, analogous to the terminator which divides day from night? (For a spherical object, this would be a great circle in the plane normal to the observer's line of sight, just as the terminator is a great circle normal to the direction of illumination.)
For the moon (on which the precise position of this line is of interest in predicting the moment of eclipse, etc) this is called the "lunar limb"
The irregularity of the lunar limb is the cause of Baily's beads.
And you can find reference to "Pluto's limb". A star is occulted when it reaches the limb of the occulting body.