In international climbing circles the term “direttissima” simply means the most direct, and often hardest, route to a summit. For example, here’s a book on the Eiger direttissima:
http://www.amazon.com/DIRETTISSIMA-...8&qid=1343002989&sr=1-1&keywords=direttissima
However, in a December 1971 story in Appalachia Magazine, Rev. Henry T. Folsom defined the White Mountains Direttissima as a continuous footpath connecting the summits of the (at the time) 46 mountains over 4000 feet, and further specified, upon throwing out the challenge to others, that whatever route chosen only include established, signed trails and roads assessable to cars. He did his route in 1969, starting at Cabot and ending at Moosilauke, taking 19 days, and spending some nights on the trail and some at home. Clearly Rev. Folsom’s route was not a direttissima in the standard mountaineering sense of the word, as that would involve a huge amount of bushwacking in the Whites.
In 2007 Mats Roing accomplished the closest I’m aware to repeating a Folsom Direttissima, continuously hiking the now 48 4000 footers in under 11 days, as reported in this thread:
http://www.vftt.org/forums/showthread.php?18251-The-48-Direttissima-in-progress-update
However, Roing used several paths, including the Lincoln Slide and the Fire Warden Trail on Mt. Hale, that Rev. Folsom probably wouldn’t have including in his definition of a White Mountains Direttissima. Not that it matters—the Roing hike was, as far as I know, the fastest continuous, and almost completely unsupported, thru-hike of the 48 4000 footers by any route.