Today's question examines the difference between libel and liable, which we'll do with some examples from The Avengers.
Our first word, libel, means "a published false statement that is damaging to a person’s reputation; a written defamation". Libel is derived from the Latin word libellus, a diminutive of liber which means "book", which makes sense given that libel relates to something which is written or published about a person. There is also a verb form of libel which means to "defame someone by publishing a libel".
"I can't believe they printed this story about Bruce and Pepper," Tony fumed. "There's no truth in it at all!"
"What story?" Steve asked.
"Will I be required to smite something?" Thor said, looking up with interest.
"I'll sue them for libel," Tony said, ignoring the interruptions. "Better yet, I'll buy the paper and fire everyone involved!"
A word which is similar to libel is 'slander', which is "a false or malicious spoken statement". So slander is to spoken statements as libel is to written ones -- and you can remember that because spoken and slander both start with an 's'.
"Does 'Iron Man' relate to your reproductive organ? Or just your brain's chemical composition?" Loki said, smirking.
"Is that slander? Or libel?" Clint said, looking at Black Widow.
"Slander, definitely. Unless you feel like writing it down for posterity, that is," Natasha replied.
There is another definition of libel, used only in admiralty or ecclesiastical law, which means "a plaintiff’s written declaration". However, unless you're going to be writing about one of those two things, it's probably a meaning you'll never use.
Unlike libel, liable is an adjective which refers to either a "responsibility by law" or something for which someone is "legally answerable". It comes from the French lier, meaning 'to bind'. When liable is used with an infinitive, it means "likely to do or be something". For example:
"Stark Enterprises is liable for any damages caused by objects falling from Stark Tower," Pepper quoted from the document she was holding.
"Stark Enterprises is what?" Tony exclaimed, turning away from what he was doing.
"I think Tony is liable to explode if Pepper keeps reading," Natasha said, smirking at Clint.
The first usage of liable is that of legal responsibility, where in this case Stark Enterprises must pay for any damages caused by objects falling from the tower. The second use of liable, made by Natasha, is that Tony is very likely 'to explode', the infinitive I mentioned, if Pepper keeps reading.
So as you can see, libel and liable have quite different meanings. Of course, they can still be confused, so you should be careful what you write, else you are liable to be libelled for any mistakes you make!
Sources
Libel definition:
http://www.oxforddictionaries.com/definition/english/libelLiable definition:
http://www.oxforddictionaries.com/definition/english/liableSlander definition:
http://www.oxforddictionaries.com/definition/english/slander