Did you know that in New Zealand, say the word 'Manchester' and everyone will think you're talking about bedsheets? Nobody will even stop to think that you might actually be referring to a large city in the North of England (which also just happens to be the home of the University of Manchester, which is in turn currently the spiritual home of Taverna).
Words often have two meanings. Taverna for instance is also a word for a certain type of Greek restaurant. It's when people disagree on the exact definition of the word, or in fact fail to authoritatively provide any definition of it, that things get confusing.
HSBC are currently running an ad campaign in which they superimpose two contrasting pictures with a single word. One of these ads at Heathrow airport shows a picture of a desert island, a teddy bear, and a webpage password prompt, all overlaid with the word 'security'. Clearly they are all valid definitions - being able to purchase and move to a remote hideaway is about financial security, the teddy is about emotional security, and the padlock is about data security. However all three definitions are clear and valid and well-understood.
Things aren't so easy with the word 'cloud' once you start to move past the strict meteorological sense. A cloud can mean a nebulous, fuzzy thing with no discernible boundaries or substance but a definite presence, as in a cloud of dust. This meaning can apply nicely to the concept of Amazon's elastic computing services, in effect hardware-as-a-service. A cloud can also mean a swarm, as in a cloud of insects, which matches nicely with research into swarm computing (particularly thinking about ant behavioural models here). A cloud can also be an opacity, as in cloudy apple juice, which matches well with the Facebook and Google model of web-hosted data accessed through software-as-a-service.
All three camps - hardware-as-a-service, software-as-a-service, and those nascent swarms of ant-like computing agents - could validly use the term 'cloud' when describing and marketing themselves. This does not make it easy for CIOs trying to identify what they really want, and even harder for them to get through all the marketing speak and understand what each vendor is truly trying to offer them.
Maybe it's time we stopped using the word 'cloud', or at least took the time to formally define it in the context of computing so that everyone would know exactly what they were talking about.