underfilter

== English == === Etymology === From under- +‎ filter. === Pronunciation === === Noun === underfilter (plural underfilters) (signal processing) A morphological filter (idempotent operator) whose image is a subset of the domain. A filter that is positioned beneath something. ==== Coordinate terms ==== overfilter === Verb === underfilter (third-person singular simple present underfilters, present participle underfiltering, simple past and past participle underfiltered) To filter insufficiently.