Meaning of SIS
What Does SIS Mean? (Using SIS Online)SIS means "Sister".
Summary of Key Points
Definition for SISSIS means "Sister". This is the most common definition for SIS on Snapchat, WhatsApp, Facebook, and Twitter. Here is some more information about SIS:
1: Easy to guess
Adults and Teenagers
A Text with SIS
Using SIS on a Cell Phone (SMS Texts, Whatsapp, and Yubl)