Teachers are constantly being told by the government they have to ensure pupils' wellbeing.
But although civil servants seem to love the buzzword, many parents, children and school staff are confused as to its real meaning.
A report commissioned by the Deparment for Children, Schools and Families has this week confirmed this.
It has suggested what many teachers already knew - that the department should be more careful using the word. It is, the report warns, extremely vague and pops up everywhere from academic reports to yoghurt adverts.
It is a key phrase in the department's 10-year children's plan, which includes a vow in its first chapter to "secure the wellbeing and health of children and young people".
Gill Ereaut and Rebecca Whiting, of Linguistic Landscapes, a research consultancy which analyses how businesses communicate with clients, warned in its report to the department that loose use of the word could cause trouble.
"Wellbeing has a holographic quality," they said. "Different meanings are being projected by different agents and what is apparently meant by the use of the term depends on where you stand. There are few fixed points or commonalities beyond `it's a good thing'. Effectively, wellbeing acts like a cultural mirage: it looks like a solid construct, but when we approach it, it fragments or disappears."
The researchers found it was not just academics and yoghurt sales teams that used different definitions. The report found the DCSF itself uses wellbeing in three different ways: in a philosophical or holistic way, in which it is used to talk about good childhoods; as an operational tool in which wellbeing is defined as the five outcomes of the Every Child Matters programme; and in an emotional or medical way. The last definition creates extra confusion because emotional wellbeing is sometimes described as one of the components of Every Child Matters, and sometimes as what all the other wellbeing indicators add up to.
They even discovered that there had been "something of a contest" between Whitehall departments in 2005 over who could define the term, with the Department of Health, the Department of Work and Pensions and the Department for Environment, Food and Rural Affairs all identifying the ways their work promoted wellbeing.
The researchers said the DCSF risked leaving children, young people and parents baffled by the term. By trying to capture the "huge and abstract ideal" of wellbeing in five Every Child Matters outcomes, the department was also claiming ownership of aspects of children's lives for which it could never be responsible.
The report said the department should acknowledge there was some ambiguity about the phrase. Rather than trying to define it, it recommends that staff be clearer about whether they are referring to wellbeing as a specific outcome or a wider ambition.
They should also drop the practice of equating wellbeing and emotional health and use more specific terms where possible.
They also suggested Ed Balls, the schools secretary, could make a wellbeing speech to clarify the term.
James Park, director of Antidote, a charity which works on emotional literacy, said: "For a long time I shied away from the term wellbeing because it was too fuzzy. It is used in many different ways, it is a bit of a bandwagon.
"We do have to use it now, because it is something that everybody is talking about.
"In public debate it's now being used to describe the Every Child Matters outcomes. It does mean it's been hijacked a bit, but so be it."
DEFINING A PROBLEM CONCEPT
"n. the condition of being contented, healthy, or successful; welfare."
(Collins Concise English Dictionary)
"Well-being is most commonly used in philosophy to describe what is non- instrumentally or ultimately good for a person. The question of what well- being consists in is of independent interest, but it is of great importance in moral philosophy, especially in the case of utilitarianism, according to which well-being is to be maximized"
(Stanford Encyclopaedia of philosophy)
"Wellbeing is a state of being with others, where human needs are met, where one can act meaningfully to pursue goals, and where one enjoys a satisfactory quality of life."
(Definition reached by an Economic Social Research Council group after five years of research)
"Arrangements are to be made with a view to improving the wellbeing of children in the authority's area so far as relating to (a) physical and mental health and emotional well-being; (b) protection from harm and neglect; (c) education, training and recreation; (d) the contribution made by them to society; (e) social and economic well-being"
(Children Act 2004, on co-operation between authorities).