ought rather formal
(used to express something that is expected or will happen)
- Children of this age ought to be able to read.
- She ought to be home by now.
(used to express something that should be done)
- He ought to be kinder to her.
- You ought to respect the law.
- She ought not to be around here.
aught old English
(anything; at all)
- Let me see if aught I can do for you.
- She doesn’t care aught for that.
for aught I know
(for all I know)
- She may be rich for aught I know. [=I don’t know if she is rich]