I have attested two words in English that come from two Latin words. These are "night" and "light". They derive from the words "nox" and "lux" respectively; both Latin — in the case of the word "nox", though, this one might also derive from Greek "nyx".

Nevertheless, the question is: is this a normal transition and happens often, or has it happened because of the word wasn't a direct loanword from Latin, but it came through other languages?

If so, do we have any other word in English that ends with -ght and its Latin counterpart ends with -x?

  • 2
    As others have pointed out, the English forms you mention are not derived from Latin. But it's not that English doesn't have forms derived from those Latin(ate) forms; just look at words like nocturnal and luminous.
    – jyc23
    Jun 12, 2011 at 1:28
  • @jyc23 - "luminosus" and "nocturnalis" are both latin words... Jun 15, 2012 at 17:08

2 Answers 2


These English words did not come from Latin. Rather, Latin and English both inherited these words from Proto-Indo-European (though not directly — there were intermediate languages). The nouns light and lux came from PIE *leuk-, while the adjective light came from PIE *le(n)gwh-. Night and nox came from PIE *nok(w)t-.

So, x did not become ght. Instead both of these words came from a language that existed about 5000 years ago; during those 5000 years, the pronunciations of the words changed many times.

It may be relevant to note that both night and light were pronounced with a /xt/ in Proto-Germanic (the language that came before Old English). It is only later on that the "gh" became silent.

(Etymology data came from etymonline.com.)


A correspondence between English '-ght' and Latin '-ex' is a bit fluid, given the vagaries of English spelling and historical phonetic and semantic drift in both Germanic and Italic and the different ways they divergesd from common Proto-Indo-European roots.

But to limit ourselves, the only three English/Latin pairs like this are night / nox, light / lux, and

right / rex.

(and this seems to have separated semantically more than the other two ('rex' = 'king' or ruler, from the past participle 'rectum' of 'rego' to rule.)

For other possible English-Latin pairs:

  • 'eight' corresponds to 'octo' (no 'x')
  • 'aught', 'naught', 'ought', 'fight', seem to be solely Germanic (see Etymonline for online references)

For Latin-English pairs:

  • 'sex' corresponds to 'six' (no '-ght' in the Engilsh)
  • 'lex' corresponds to 'law' (which are cognate
  • 'crux' corresponds to 'cross'
  • 'vox' corresponds to 'voice'

Whenever these are pairs, I've only given actual cognates, but the phonetic or spelling rules diverged from the ght/x pattern.

  • The base form of lex (law) is "lex, legis (leg-)" which is the root of the English word legal. Jun 15, 2012 at 17:07
  • @Adam: yes, the PIE versions of all of these have a velar followed by a dental. In English (in Germanic) and in French (in Romance) the velar experienced lenition (lenited?). 'legal' is simply a modern professional/academic creation/borrowing directly from Latin.
    – Mitch
    Jun 15, 2012 at 20:28

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