Night carries the most famous silent digraph in English. The gh once stood for a real sound, a rasp at the back of the throat like the ch in Bach — Old English niht was said with it, and so was Middle English. The sound died out across most of England between about 1400 and 1600, but printing had fixed the spelling first, so the letters remain as a record of a pronunciation no English speaker has used for four hundred years.
The word is ancient and shared: Old English niht, German Nacht, Latin nox, Greek nyx, Sanskrit naktam, Welsh henoid, all from an Indo-European root that probably meant "to be dark." Almost every Indo-European language kept it, which is what you expect of a word for a thing that happens every day. The modern English vowel comes from the oblique cases of the Old English noun rather than from its base form.
night (n.) late Old English niht (West Saxon neaht , Anglian næht , neht ) "the dark part of a day; the night as a unit of time; darkness," also "absence of spiritual illumination, moral darkness, ignorance," from Proto-Germanic *nahts (source also of Old Saxon and Old High German naht , Old Frisian and Dutch nacht , German Nacht , Old Norse natt , Gothic nahts ). The Germanic words are from PIE *nekwt- "night" (source also of Greek nyx "a night," Latin nox , Old Irish nochd , Sanskrit naktam "at night," Lithuanian naktis "night," Old Church Slavonic nosti , Russian noch' , Welsh henoid "tonight"), according to Watkins, probably from a verbal root *neg- "to be dark, be night." For spelling with -gh- see fight . The vowel indicates that the modern English word derives from oblique cases (genitive nihte , dative niht ). The fact that the Aryans have a common name for night, but not for day (q.v.), is due to the fact that they reckoned by nights. [Weekley] Thus in Old English combinations night was "the night before (a certain day or feast day);" compare German Weihnachten "Christmas," literally "holy night." In early times, the day was held to begin at sunset, so Old English monanniht "Monday night" was the night before Monday, or what we would call Sunday night ; so saeterniht "Friday night." Thomas à Becket's Wednes-night (Old English Wodnes-niht ) would be our Tuesday night. The Greeks, by contrast, counted their days by mornings. To work nights preserves the Old English genitive of time. Night soil "excrement" (1770) is so called because it was removed (from cesspools, etc.) after dark. Night train is attested from 1838; night-school from 1520s; night-life "habitual nocturnal carousing" is attested from 1852.
night came in through Old English, and its spelling follows that family's conventions.
How that family writes these sounds
| a vowel that runs longer than it should, before nothing you can hear | gh — silent, or said as flight, night, daughter, enough |
Old English in the spelling guide · guess another word's family