ONE of the things journalists have to learn, and pretty quickly, is the difference between tax avoidance and tax evasion. The former means exploiting the system to find ways to reduce how much tax you owe; the latter means concealing income or information from the HMRC. It is illegal.

In other words, tax avoidance may be considered by some to be morally dubious, but you're not going to be locked up for it. Hopefully, you would be for tax evasion, though the authorities don't seem to have a great track record on that score.

There has been a similar lexical conundrum of late concerning the actions of certain politicians. The word of the moment has been "sleaze". But thrown into the mix by several commentators and correspondents has been the term "corruption". It should be noted that the two are not always interchangeable, and are subject to degrees of interpretation.

The Cambridge Dictionary defines "sleaze" as "activities, especially business or political, of a low moral standard". "Corruption" meanwhile, is rendered "illegal, bad, or dishonest behaviour, especially by people in positions of power". It is that illegality aspect that means we ought to tread carefully.

(Incidentally, this newspaper carried a headline the other day which read: "Storm over Tory ‘sleaze’ sees call for criminal probe by Met boss". I struggle to see the justification for the inverted commas, since the fact of sleaze was hardly in doubt.)

There are other terms we have seen in the political discourse that are perhaps employed too carelessly. "Criminal" for one. People do sometimes describe the Government (I'll let you decide for yourself which one) as "criminally inept". Now, ineptitude is not always punishable by law, though there is such a thing as criminal negligence.

Another is "liar". It is quite something to accuse someone of lying, as opposed to being, ahem, economical with the truth. We can all probably think, though, of a certain politician who has been proven to have deliberately lied. I do not think it necessary to excise the description in such cases.

That term "economical with the truth", made famous in the UK by the then Cabinet Secretary Robert Armstrong during the 1986 Spycatcher trial in Australia, has a charm that a bald "lying" can never have. Perhaps we should have more of them.

His remark is almost equalled by Hillary Clinton's assertion that she "mis-spoke" when she falsely claimed to have been pinned down by sniper fire while on a trip to Bosnia. And does anyone remember Private Eye's "discussing Ugandan affairs" to denote extramarital shenanigans? Or "tired and emotional" to describe someone, famously Labour's George Brown, who is rolling drunk?

Maybe instead of calling a politician a crook and a liar, we might say something along the lines of he or she being morally disadvantaged. Our lawyers might thank us for it.