If you sidle somewhere, you walk there in a quiet or cautious way, as if you do not want anyone to notice you. A young man sidled up to me and said, `May I help you?'. to walk towards something or someone slowly and quietly, as if you do not want to be noticed sidle up/towards/along (Probably from sideling (14-19 centuries))
sidling
النطق
علم أصول الكلمات
() cognate with the above (by back-formation from its form sideling)