I've read lots of definitions of 'project'; so have you, I'm sure, but I've never been content with them: mostly they are boring statements of the obvious, along the lines of 'a project is a temporary effort with a start and a finish that...'
Currently reading Shenhar's Reinventing Project Management, I came to my own take: the deployment of resources to profitably change an organisation's capability. The organisation might be the project sponsor, or a client.
The core of a project is that a change or opportunity (which arises inevitably from a change) in the (business) environment creates the ground for deployment of resources to stabilise the organisation's interaction with the environment-now-changed (or about to be changed) in line with the organisation's strategy or mission, which itself may be changed by the project.
Projects provide capability, operations use it.