Adsorb

Part of speech: verb

Pronunciation: /ədˈzɔːb/

Definitions

1. To collect and retain molecules on a surface rather than allowing them to penetrate further into the material
2. To trap and hold particles on a surface through physical or chemical interactions without becoming part of the bulk
3. To attract and hold molecules or particles on an outer layer without absorption

Etymology: The verb "adsorb" is built from two Latin pieces: "ad-", meaning "to", and "sorbeō", meaning "suck in" or "swallow." The Latin verb is the source of a whole family of English words about soaking up and taking in, including "absorb," which shares the same root "sorbeō" but with the prefix "ab-" meaning "away" in place of "ad-". The two words are close relatives that diverged in meaning: "absorb" describes material being drawn fully into something else, while "adsorb" describes the opposite-facing action of holding material on a surface. Scientists needed that distinction. The word passed into English from French "adsorber", and its sense in English is the specialized one of particles gathering on a surface rather than sinking into the interior. A sponge absorbs water into its body, but activated charcoal adsorbs gas molecules onto the enormous internal surface of its pores. The single letter change from "b" to "d" in the prefix is what separates the two processes.

Synonyms: attach, adhere