"DOCTOR, Doctor, I'm only five foot tall." "Then you'll just have to be a little patient," comes the reply. But will they? In the battle that is life, it is important to know which you are: patient, client, or customer.

Hospitals and doctors seem to have patients, but therapists tend to have clients. These clients may be more unwell than many patients in A&E; but professional respect is involved. If you are visiting a therapist, you are probably middle-class, with certain requirements as regards status. There is no way that you are going to be called a patient; that might suggest that there is something wrong with you.

The word comes from the Latin clientem, meaning follower, or retainer, with a sense of one who needs protection. But the shift occurred in England when, in the late Middle Ages, it came to mean a lawyer's customer, which is soothingly middle-class.

So now recruitment agencies have clients, as have financial advisers. And, if you sack me, I take my "client-base" with me, as opposed to my customers; to call them that would be professional suicide. So, then, who has customers?

Supermarkets have customers. It came to mean "buyer" in the 15th century, from the Old French costume, meaning custom, or practice. It described people who turned up and bought things regularly. (Although - whisper it quietly - in Shakespeare the word could also mean "prostitute".)

All the labels are, of course, interchangeable. Having worked in supermarkets, I feel that "patient" is more accurate than "customer". The reverse is true in hospitals, who now talk eagerly about the patient as "customer", as someone who has rights in this healing transaction.

In ten years' time, when the NHS no longer exists in anything but name, it will probably have "clients", and schools will follow suit. Even now, there are schools that have exchanged "parents" for "customers". As one head teacher told me: "Everything in this school is about the customer. The teachers have to appreciate that, and deliver." As in the world of retail, so in the world of élite education: what the customer wants, the customer gets.

In the mean time, you have "friends" on Facebook; and on Twitter, you have "followers". In the Church, pew-punters down the centuries have tended to be called "sinners" - a useful epithet for the hierarchy, which keeps the masses suitably abject. But these days the obsession with sin works only for a particular grouping; so a new language must emerge - although I still cannot imagine St Michael and All Angels' having "clients".

Patients have needs; clients have status; customers have rights. Perhaps, added together, they become the word "human", all sawdust and glory.