/ Dictionary / Index R rheumatoid factor: Meaning and Definition of Find definitions for: rheu'matoid fac"tor Pronunciation: [key] — Biochem. Biochem. an antibody that is found in the blood of many persons afflicted with rheumatoid arthritis and that reacts against globulins in the blood. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. rheumatoid arthritis rheumatoid spondylitis Related Content Daily Word Quiz: dissonant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language