used to say that someone does something because of the reason just stated:
I was feeling hungry, so I made myself a sandwich.
in order to make something happen, make something possible etc:
He lowered his voice so Doris couldn't hear.
Why don't you start out early so that you don't have to hurry?
used to say that something happens or is true as a result of the situation you have just stated:
There are no buses, so you'll have to walk.
The gravestones were covered with moss so that it was impossible to read the names on them.
used to introduce the next part of a story you are telling someone:
So anyway, he goes in and his boots get stuck in the mud.
4 also so what? spoken not polite
used to tell someone that something does not matter:
• So what if we're a little late?
• 'She might tell someone.' 'So? No one will believe her.'
in order to do something:
I drove at a steady 50 mph so as to save fuel.
We went along silently on tiptoe so as not to disturb anyone.
used to compare two people or things, when they are similar:
Just as the French love their wine, so the English love their beer.