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Kinematic distance is a distance-determination to an object within the Milky Way based upon a map of the general movements (orbits) of objects within the galaxy. In any given direction, the typical radial velocity of an object varies with distance due to the object's orbital path around the galactic center, and the general relation between typical orbits and distance from the center is known. Since Doppler shifts of recognizable spectral lines gives very good information on radial velocities, this is very useful for determining the distance to clouds, which do not offer the clues to distance offered by stars (stellar distance determination).
The Kinematic distance ambiguity is a distance ambiguity in that in some directions, there are two different distances at which the expected radial velocity is the same, thus two different distances are consistent with the radial velocity. For clouds, finding methods based on observation to resolve this ambiguity is of interest.