These words refer to the execution of a systematic plan for realizing an explicit objective. Project and programme might both seem to refer literally to a proposed plan rather than one being carried out, but in actual usage these words can apply to such a plan at any stage of its existence, from conception to completion. Project is the more general of the two words and can apply equally well to the planned task of a single person or to such a task involving a number of people: a project to teach himself French at weekends; the government’s highway-construction project . The word is often used to refer to the end result of such work, long after its planning and completion: the six-block housing project . Programme is more formal and more abstract than project and applies most often to group work. Where project might suggest a single self-contained objective often requiring physical labour, programme can suggest a more complex set of such projects or the application of largely mental or administrative effort: a regional development programme that would involve a number of local projects .

Activity is the most general of these words. While it need not suggest any plan or objective at all, it is often used to refer to the work done on a project or carried out by a group. It stresses the actual carrying out of something that simply continues without any point of completion: kindergartens that emphasize unprogrammed play time activity . University students who neglect their studies for extra-curricular activities ; community centres offering such activities as language classes, art courses and dancing.

Operation is close to activity in its generality, suggesting continuing motion without necessarily implying the possibility of completion: studying the operation of the arbitration courts. It has come to have a special use in reference to a complex programme designed to achieve a clearly defined goal; this use, borrowed from the military, follows the capitalized word with a colourful epithet: Operation Crossbow.

Enterprise and undertaking are the most formal of these words. Enterprise may suggest improvisation towards a less clearly defined goal and may imply an element of risk; it may also suggest boldness and strenuous endeavour: a perilous enterprise that few thought could succeed. On the other hand, it may simply refer to any business activity.

• Watch-making and banking are the chief enterprises of the country.

Undertaking is more general than enterprise , but unlike activity it suggests both considerable forethought and the possibility of completion: agreeing to the undertaking only after exhaustive discussion of other alternatives. It can sometimes sound like an unnecessarily fancy substitute for one of its less formal synonyms.