The distinction between "famous" and "infamous" can trip up even the most judicious writer. How can two letters cause such a headache? Allow us to shed some light on the subject so you use these two correctly and avoid mislabeling a modern saint as "infamous."
"Famous" is a word that describes something or someone with a lot of influence and followers. Someone is famous when lots of people know them. Actors, singers, political leaders, even cities can all be described as famous. This all seems obvious, right?
A person can be famous for being a good and kind person, but being famous does not necessarily relate to behavior — though the word is, more often than not, used in a positive manner.
"Infamy" means a despicable reputation. Therefore, "infamous" is entirely negative. There is no wiggle room here. Pearl Harbor is often used as an example since President Franklin Delano Roosevelt referred to it as “a day which will live in infamy” — a phrase you've no doubt heard. You wouldn't call a wonderful, momentous day that all will remember "infamous."
Although the two words come from the Latin "fama," meaning "fame," you can see that "infamous" is not the opposite of "famous." The opposite of "famous" is "not famous," which doesn't come close to describing an infamous person or event.