Paraglobulin

Part of speech: noun

Definitions

1. A protein belonging to the globulin fraction of blood plasma, separated from other plasma proteins in laboratory analysis
2. Any of the blood plasma proteins classed as globulins, sometimes distinguished from albumin and fibrinogen in clinical testing
3. A plasma globulin that is one of the proteins measured when doctors study the makeup of a patient's blood serum

Etymology: Paraglobulin is a technical coinage, and its history is simply a matter of combining two existing parts. The second part, "globulin", names a class of proteins found in blood plasma and other body fluids, and it comes from "globule", a small round drop, from Latin "globulus", a diminutive of "globus", meaning ball or sphere. The first part, "para-", is the Greek prefix meaning "beside", "alongside" or "beyond", and in chemistry and biology it signals a closely related substance or a variant of one. Put together, "paraglobulin" names a particular kind of globulin set apart from the others. The word belongs to the vocabulary of protein chemistry and clinical laboratory work, where blood proteins were separated and named according to their behaviour and solubility. It is a precise label rather than a word with a long popular history.