Retsim Share definition Flag Mister backwards. Commonly used jointly with Sussim (Ms. backwards). Particularly handy when describing a couple that cannot be openly discussed. I saw Retsim and Sussim wearing hideous matching sweaters today. Retsim by Billiken May 4, 2004 0 0 Get merch Get the Retsim mug. Buy Now — $32.95 See more merch