Antigenicity

Part of speech: noun

Definitions

1. The trait of a substance that leads to an immune response in the organism
2. The characteristic of a molecule or substance to be recognized by the immune system and provoke a defensive reaction
3. The quality of an agent that induces the immune system to identify and respond to it as foreign

Etymology: Antigenicity is a plain modern compound, built by adding the suffix "-ity" to the adjective "antigenic." That adjective is itself made from "antigen" plus "-ic," and the suffix "-ity," which turns adjectives into nouns of quality, came into English through Old French from Latin "-itās." So the word's real interest lies in its parts rather than in any single surprising turn. The first element, "anti-," comes from Ancient Greek "ἀντι-," meaning "against" or "opposite to." The second, "gen," comes from the Greek root meaning "to produce" or "to give birth," the same root behind words like "genesis." Combined, "antigen" describes a substance that prompts the body to produce something against it. French scientists formed "antigène" in the same spirit, and English borrowed it as "antigen." Antigenicity therefore names the quality of being able to trigger that defensive reaction. Its suffixes are all borrowed or inherited long before the word existed: the Latin "-icus" and the Latin "-itās" were attached to older Greek and Latin roots, and the modern term was assembled from them in a laboratory vocabulary.