The editors of the New Oxford American Dictionary chose refudiate as their 2010 word of the year, and now the editors of the Oxford English Dictionary have added knowledgeful to the OED, making it an officially-sanctioned proper English word, even though our spell-check program disagrees with the validity of both words. This second word, however, has a long history in the English language and a sound grammatical foundation.

The word knowledgeable is the word most of us think to use today when we want to express the concept of “full of knowledge on a topic.” But when we look at the suffix of the word, we see -able, which is the suffix used to indicate “capable of being [root word].” In this case, knowledgeable originally meant “capable of being known.” The suffix -ful, on the other hand, means exactly what you might think: that something is “full of [root word].” Therefore, back in the 17th century when both words were in use, it was correct to say that the total number of eggs a hen laid in a year was knowledgeable – a person could count the eggs and know the total – and also correct to say that a farmer whose hens laid more eggs than average was very knowledgeful about chickens and how to raise them.

Other older formations of words may eventually come back into common use in the future. Back in 1661 the London writer Samuel Pepys described a sermon as being “good, honest, and painfull,” meaning that the author of the sermon had taken great pains (been very careful in research and creation) in its composition. These days, if we say a speech is painful, it means it’s hard to listen to, rather than being admirable (capable of being admired – there’s that suffix again!). The English language is always evolving, and sometimes that evolution is a revolution, bringing back words from the past to enrich our present vocabulary.