Which word has three consecutive pairs of letters? This means that it would have the form ---XXYYZZ---, where X, Y, and Z are any letters.

Bookkeeper

Bookkeeping

Bookkeeper is the word with 3 pairs of consecutive letters.

If you want to get a little esoteric (and a little disputed):

You can go one pair better than that! subbookkeeper is the only word found in an English langauge dictionary with four pairs of double letters in a row. This word is in W2, but is not in W3 or OED2.

http://www.definition-of.com/subbookkeeper

WOOLLOOMMOOLOO, according to the Australian Encyclopedia and various editions of Encyclopaedia Britannica, is the original spelling of Woolloomooloo, a suburb and bay in Sydney, Australia