In his Dictionary of the English Language, the first if its kind, Samuel Johnson defined dull as "not exhilarating; not delightful; as, to make dictionaries is dull work." Yet in his dictionary, Johnson did his best to relieve the dullness with his witty and creative definitions. Maybe he wasn't quite the wit Ambrose Bierce was in his The Devil's Dictionary many years later, but still he was pretty good. Vivian Cook offers some examples in It's All in a Word.
In another joke at his own expense, he defined lexicographer as "a writer of dictionaries; a harmless drudge."
Johnson said of oats that it is "a grain, which in England is generally given to horses, but in Scotland supports the people."
He defined a politician as a "man of artifice; one of deep contrivance."
A network, he wrote, is anything "reticulated or decussated, at equal distances, with interstices between the intersections." We can just imagine how he must have laughed over that one.
Johnson used his dictionary not just to make jokes, but also to express opinions. He described lesser as "a barbarous corruption of less" and astrology as "the practice of foretelling things by the knowledge of the stars: an art now generally exploded as without reason."
As for sonnet, he called it a "short poem consisting of 14 lines ... It is not very suitable to the English language, and has not been used by any man of eminence since Milton."
Modern dictionaries are more objective, more accurate and more balanced, but they are also more likely to fit Samuel Johnson's definition of the word dull.