Brain Teaser...can you guys help??

I am planning to compile a list of words where in if you replace only one letter the meaning of the word changes completely.

For eg: bitter & better,

Can you please add???

Kasturi: Sample & simple
             Ride & rude
             Line & lone
             liner & liver
             Taunt & gaunt......

I think, better would be if they are opposites!!!!!...Kasturi's wont help!!!!

Karthik: side tide

             site side

             tide hide

             tide wide.....

Not accepted.....