The estimation of higher spectral frequencies than any actually measured. Superresolution can sometimes be achieved using nonlinear image restoration techniques such as CLEAN. However, for CLEAN, superresolution is untrustworthy unless the signal-to-noise ratio is very high and uv coverage is very good. Superresolution can often be achieved with maximum entropy method. Eric Weisstein's World of Math
References
Pearson, T. J. and Readhead, A. C. S. "Image Formation by Self-Calibration in Radio Astronomy." Ann. Rev. Astron. Astrophys. 22, 97-130, 1984.
