A term appearing in Notes on Names (NN) from 1957 (PE17/139). It had the singular forms belerion, belerieth, belair and plural forms belair, balarwaith, beleriath. It appears to be a name used for the Sindar in contrast to the Noldor and Nandor. It perhaps refers to the island of Balar from which Beleriand was named; hat-tip to Parmandil for this suggestion.