Videlicet means 'namely' or 'that is to say'. You use it before naming exactly the thing you have just referred to in general terms: 'the accused failed to appear on the date set, videlicet 4 March 2019'. It is almost never written out in full. In practice you meet it as the abbreviation viz., and the strange thing is that when people read viz. aloud, most of them say 'namely', not 'videlicet' — the abbreviation is a written signal rather than a spoken word. This is a lawyer's and scholar's word, formal and dated, alive mainly in legal documents, old academic writing and pedantic footnotes. Everyday English simply says namely, that is, or in other words. It helps to hold it next to its two Latin neighbours, which students constantly muddle: i.e. means 'that is' and restates the same thing in other words; e.g. means 'for example' and gives one or two of many; viz. names the full list or the exact item you meant — so it is closer to i.e. than to e.g., but with the flavour of specifying rather than explaining. The odd-looking abbreviation, by the way, is not a typo: the z is not really a z but an old scribal mark standing for the -et ending.

即、也就是說（正式的拉丁語詞，幾乎只以縮寫 viz. 出現在法律或學術文件裡；唸出來時多半直接讀成 namely。日常英文說 namely 就好）