RI

radiation intensity; radioactive isotope; radioimmunology; recession index; recombinant inbred [strain]; recurrent inhibition; refractive index; regenerative index; regional ileitis; regional information system; regular insulin; relapse incidence; relative intensity; release inhibition; remission induction; renal index; renal insufficiency; replicative intermediate; resistive index; resistance indices; respiratory illness; respiratory index; response interval; reticulocyte index; retroactive inhibition; retroactive interference; ribosome; rosette index (or inhibition)