The act of cutting the end off something so that it becomes shorter, or the shortening that results. It is the noun of 'truncate', and it is a formal, technical word — you meet it mostly in computing and mathematics rather than in speech. In computing it names a very ordinary problem: text or a number is too long for the space it is stored in, so the extra is thrown away, and 'truncation' is what you call that loss. In mathematics it means chopping a number off after a certain place instead of rounding it — truncating 3.87 to one decimal gives 3.8, while rounding gives 3.9, and that difference is why the word matters there. Outside those fields it can describe any unfinished stopping — 'the truncation of the trial', 'the truncation of his studies' — but a plain English speaker would more likely say 'it was cut short'.

截斷、截短（電腦與數學用語）