When do you add “-ly”?

Today, an American Airlines jet blew out a tire and had an engine malfunction at O’Hare Airport.  A fire broke out and all passengers were evacuated, with only a few sustaining injuries.  Ms. Ditz, the perky, young TV news reporter on the scene, told us an expert source had assured the media that events like this “seldomly” occur.

Adverbs tell us when, where, and how (e.g., later, inside, almost).  English grammar rules allow us to form some adverbs by adding –ly to adjectives (e.g., beautifully, softly, quickly), but who knew we had to do that to words that are already adverbs (e.g., seldom)?

Fortunately for her, Ms. Ditz appeared to be untroubled about sharing her ignorance with her viewers.  Perhaps, if she knew anything at all about English grammar, she might even be proud of inventing a ninth part of speech:  the redundant adverb.