Noun
English Wikipedia has an article on:undersamplingWikipedia
undersampling (countable and uncountable, plural undersamplings)
sampling at a lower rate than normal
Although aliasing in most systems is unwanted, it should also be noted that it can be exploited to provide simultaneous down-mixing of a band-limited high frequency signal (see undersampling and frequency mixer ). Source: Internet
However, Pap smears are very sensitive and some negative biopsy results may represent undersampling of the lesion in the biopsy, so negative biopsy with positive cytology requires careful follow up. Source: Internet