I'm coming to this discussion late in the game, but just to put my two cents in, a lot of what people THINK of when we say the word cutlass has been shaped by the movies. And the reason the pirates (and the sailors on the HMS Bounty, and about anyone else who used a sword at sea during the golden age of Hollwood) used the classic Cup-Hilted Cutlass was that the studios has bought out the Navy Cutlasses that were surplus from the Civil War. So art retro-fired back into history and no one can imagine a pirate without a cup-hilted cutlass.
As to the cutlass vs. hanger debate, I think cutlass was probably not a universal term during the GAoP and is one we are imposing on a class of weapons from our perspective. I have a English seaman's sword that I would call a cutlass, c.1690. It has a dog-head pommel, decorated cast brass grip, shell guard, and curved falchion-type blade stamped with fleur-de-lys mark. But the Board of Ordinance called it a "brass hilted hanger." It was likely part of a procurment in 1692, as suggested by inventory entries at the Tower of London. Other contemporary references to "dog-headed hangers" suggest this example as a ship's issue cutlass of the period. This sword is of a type found in period sea wrecks dating to 1694 and 1703. (See Gilkerson, Boarders Away, With Steel. p. 74, no. 3.)
BTW, Gilkerson, (who is not always right) accounts this way for the cutlass etymology: "from the Latin cultellus, for short sword the Oxford dictionary notes the first appearance in old English as curleax in 1579, and another spelling as court-lace in 1594. By the 18th century the word had come to be generally applied to the short hangers favored by seamen, and it is seen in other spellings such as cutlash in contempoary documents." (p. 72)
It was also well known for ordinance boards to secure infantry hangers for seagoing use. This happened in the case of the English 1742 Pattern Infantry Hanger, which was appropriated and marked for Naval use in the 1770's. In 1755 the Swedish Admiralty ordered its ship's issue cutlass to be the Army's Infantry Briquet of 1748. (The design was very similar to the British 1742.) This brass-hilted hanger would remain the primary Swedish Naval cutlass through the Napoleonic Wars.
You say cutlass, I say hanger, you say tomato...... And I've run you through!
You can see my cutlass (or my hanger) ;^)~ here:
http://www.flickr.com/photos/49474691@N04/4664522043/sizes/z/in/set-72157624192492852/
Black Mark Morgan