In a recent defence of double negatives I mentioned litotes in passing; this post will look at it in greater detail. Since the word is more often read than heard, and its appearance may mislead, we should start with pronunciation. Litotes has three syllables and is normally pronounced either /laɪˈtəʊtiːz/ ‘lie-TOE-teez’ or /ˈlaɪtəʊtiːz/ ‘LIE-toe-teez’, with minor variations. It is totes not a two-syllable word rhyming with oats, as I once thought.
Now that we know how to say it, what does it mean? Litotes is defined by Macmillan Dictionary as ‘the use of a negative statement to say something positive, for example by describing something as “not unreasonable”’. So it’s a kind of understatement or assertion made by negating an opposite: This is no small matter = This is significant. He’s not the worst = He’s OK. It often takes the form not un-. She was not unhappy. The house was not untidy. By using the negative words but contradicting them, these phrases understate the descriptions. Not unhappy is not quite happy; not untidy falls short of pristine.
Litotes has been a feature of English for many centuries and is less rare than you might think – indeed, it is anything but uncommon. Litotes is used in all sorts of language varieties and contexts, from high-flown rhetoric to everyday small talk. We might reply to the greeting ‘How are you?’ with ‘Not bad’ or ‘Can’t complain.’ To indicate that something is good or worthwhile, we can say it is no harm: ‘A: Will it rain? B: No harm to bring in the clothes anyway.’
Litotes shows up in some familiar phrases and idioms. If we think someone should be able to do or understand something, we can say it’s not rocket science. If someone has overstepped the mark, we can let them know in no uncertain terms – a phrase that conveys the force of our disapproval. So as well as understatement, litotes can also be used for emphasis.
For example, in the song ‘No Ordinary Love’, Sade uses litotes to express the intensity of the love she feels – like saying it’s extraordinary, but with a different effect. The contradiction arrests our attention, like a rhetorical tension set up then resolved. In the comedy film Ferris Bueller’s Day Off, the school principal uses litotes for ironic emphasis when he says Ferris ‘does not have what we consider to be an exemplary attendance record’. Here’s it’s a kind of irony.
Just how emphatic or understated the effect is depends on the context: not bad could mean barely acceptable, average, good, or outstanding, depending on intonation and circumstances. Some critics warn against overuse of the technique, but overuse by definition implies excess. There’s nothing inherently wrong with litotes.

[…] further about a particular form of multiple negation that has been popular for many centuries. In Litotes is no small matter, at Macmillan Dictionary Blog, I describe this figure of speech […]
Is it idiomatic for you to follow no harm by the infinitive? For me, no harm pretty much has to be followed by in and the -ing form: no harm in bringing in the clothes anyway.
John: Yes, it’s fine for me – and, I suspect, for any Irish English speaker. No harm in __ing is fine here too, but I favour the infinitive form.
I quite agree that ____ing is harmless.