Also found in: Dictionary, Thesaurus, Legal.
To keep something from being known or experienced. A noun or pronoun can be used between "filter" and "out." These must not be noise-canceling headphones because they're not filtering out any of conversations currently going on around me in the coffee shop.
To prevent something from passing through, being communicated, or being perceived: My new glasses filter out ultraviolet rays. These headphones filter unwanted noise out.