There is a little group of irregular verbs in English that follow a similar pattern, having "-ught" as their ending for past simple and for participle.

These verbs are among the group of most used verbs in the language, so one gets the impression that they could be the vestige of some ancient feature of English.

Among these verbs, these can be listed:

  • Bring   →   brought
  • Buy   →  bought
  • Catch   →  caught
  • Fight   →  fought
  • Seek   →  sought
  • Teach   →  taught
  • Think   →  thought

Another feature, common to all of the verbs above, is that they don't have different forms for past simple and participle.

Is there any reason for these verbs to "behave" this way?

P.S. One can go even further, and notice that the characters just before this ending, can be either a or o.

  • 2
    Catch → caught is a little bit different from the other strong verbs you cite. It actually comes from Old French chacier (Modern French chasser which also produced to chase). The past participle used to be catched but later evolved into caught for some reason. I can't see any influence of other verbs with the same ending: matched, patched, attached are all regular. Commented Mar 4, 2015 at 2:47
  • 3
    @Alain The native English verb that catch displaced was latch, which is weak now, but had a strong past læhte in Old English and probably influenced the strong conjugation of catch. Commented Mar 4, 2015 at 3:04
  • 3
    Note cognate verbs of some of these are irregular weak ("mixed") verbs in German: bringen, brachte, gebracht; denken, dachte, gedacht. It's easy to see the original /k/ or /g/ that decayed into /x/ through Grimm's Law, and then flew away completely in English speech with the loss of the [ɣ] allophone of /h/ (which is where all those wierd English GH spellings come from, btw). Commented Mar 4, 2015 at 3:19
  • And work; wrought. Commented Mar 4, 2015 at 3:32

1 Answer 1


In general, these verbs used to end in a "g", "k" or "ch" /tʃ/ sound. In some of the modern forms of these words, this sound has changed, such as in "buy".

"fight"~"fought" is not related to the others

You can see that "fight" ends in "ght" in the present as well as the past. It belongs to the large category of English verbs that mark the past tense with a vowel change rather than a dental suffix, like "ride" and "rode". These are called "strong verbs", and the vowel alternation is called "ablaut".

The "t" is the past tense suffix (in words other than "fought")

The "t" added to the past tense in the other words is just a form of the usual dental-consonant past tense suffix, as in "burnt" or "learnt", that is characteristic of "weak verbs".

The "gh" represents historical /x/ from earlier /k/ or /g/

In older forms of English, the "k", "ch", "g" and "y" sounds alternated in some words with the sound /x/, a velar fricative (like the ending sound of "Bach" in German). This sound is produced in the same place in the mouth as the k and g sounds (/k/ and /g/ are velar plosives).

The reason for this alternation is a historic sound change shared by all the Germanic languages that turned either of the velar plosives "g" or "k" into the velar fricative /x/ before another consonant. The "ch" /tʃ/ and "y" /j/ sounds are also involved in this alternation because these sounds developed in English from earlier Germanic /k/ and /g/ respectively in palatalizing contexts.

So, the "gh" represents the sound /x/, which was still pronounced relatively recently in English, for example in Chaucer's time.

Except "caught" never actually had /k/

The word catch was borrowed into English from French with the "ch" sound /tʃ/. It developed a past tense form with "gh" /x/ by analogy with similar verbs.

The "ou" or "au" is due to sound changes that occurred before /x/

Before the sound /x/, nasal consonants such as "n" were regularly dropped, which is why you don't see the "n" of "bring" and "think" in their past tense forms.

A later sound change involving /x/ caused a preceding vowel to develop an offglide. This is why "u" shows up before the "gh". You'll notice that silent "gh" is always preceded by "u" or "i" in the spelling of ordinary Modern English words. (Some of these words also had more complicated vowel changes in the past tense from earlier on in their history.)


Except for "fought", which is just ablaut, the reason why the sequence "-ught" shows up in all these words is basically because

  • the "t" is the past tense ending
  • the "gh" is a remnant of what became of the last consonant of these verb's present-tense forms
  • the "u" reflects the effect the formerly-pronounced "gh" sound had on the preceding vowel.
  • 5
    The way you've phrased it here makes it sound like your relative chronology is reversed. The chronological order was that /k, g/ were both fricativised before /t/, yielding [x, ɣ]. This happened already at a pre-English stage. Then later on, in English, the /k, g/ that weren't followed by /t/ and were still plosives were palatalised and affricates before front vowels, yielding [t͡ʃ, d͡ʒ] in Old English, at which point synchronically it looked like [t͡ʃ, d͡ʒ] alternated with [x, γ]. Apart from that, +1! Commented Mar 4, 2015 at 2:59
  • @JanusBahsJacquet: I realized that problem partway through writing it, which is why I wrote "alternated with a kh-like sound" rather than "changed to a kh-like sound". It's a fair criticism though -I definitely simplified the situation some in this explanation!
    – herisson
    Commented Mar 4, 2015 at 4:08
  • @JanusBahsJacquet: "yielding [x, ɣ]." Wouldn't voicing assimilation have caused these to both be neutralized to [x] in this context? As far as I know, [ɣ] was just an allophone of [g] in OE, so it would have been written with <g> and not <h>.
    – herisson
    Commented Mar 4, 2015 at 5:00
  • Different Germanic languages deal with the distinction between the two in different ways, so at the time when the fricativisation first arose, there must have been a distinction. Later on (probably in common West Germanic, but hard to tell), voicing assimilation came in and took over, so then it was just [x] regardless of whether it was originally /k/ or /g/. The last [ɣ] in Old English shouldn't have been there, that's true—it only belongs in the pre-English stage. (And typing IPA on a phone is a mess, so I think I accidentally typed gammas instead of IPA fricatives.) Commented Mar 4, 2015 at 10:49
  • 1
    @Janus Bahs Jaquet How do you type IPA on an iPhone? Commented Mar 16, 2015 at 21:00

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.