When you are not fullysuperstitious. If you're just a little superstitious you're merely stitious.
My friend would neverwalk under a ladder because he is very superstitious. I would think about it but probably not pay much attention. I'm only stitious.
Mom always throws salt over her shoulder when cooking, but swears she's not superstitious. She is at least stitious because i've see her do it all my life.