A summing-up is a short speech or statement at the end of something, giving the main points and leaving out the details. Its home is the courtroom: after both sides have spoken, the judge gives the summing-up — going back over the evidence, explaining the law, and telling the jury what they must decide. That is the strongest and most technical use, and it is British legal language (in American courts, the lawyers' final speeches are called 'closing arguments', and the judge gives 'jury instructions'). Outside court, people borrow it for the closing part of any long discussion: the end of a meeting, a debate, a conference, a report. 'In his summing-up, the chairman said the project should go ahead.' The plural is 'summings-up', which sounds odd but is correct — the 's' goes on the noun part, as in 'passers-by'. It comes from the verb phrase 'sum up', meaning to give the main points briefly, and you will hear that verb far more often than the noun: 'To sum up, we need more time and more money.' Note that a summing-up is meant to be fair and complete in its shape, not just short — a judge who leaves out something important can have the whole trial overturned.