513: fault May 4, 2016

'Fault' comes from the Middle English word 'faut(e)' which meant ‘lack, failing’, and was based on the Latin, 'fallere' meaning ‘deceive’. The letter L was added in English and also French in the 15th century in order to create a stronger association with the Latin word, but that did not become standard in English's standardized spelling until the 17th century, though it was not pronounced until the mid-to-late 18th century.