RSL UK /ɑː ɛs ɛl/US /ɑɹ ɛs ɛl/ noun4 •(Australia) A club run by the Returned and Services League of Australia.So anyway, Gibbsy and I are in the R.S.L. and I'm having a shocker. — 1995 •Initialism of Russian Sign Language. •Initialism of regional screening level. •Initialism of recurrent slope linea. formsRSLs