Phonologically,« lire » and « rire » sound like a minimal pair, with the first letter as the only difference. So what might explain the difference between their « participes passé »?
Their etymons are Latin.

Reply to comment by user 'sumelic': I'm inexperienced in Latin; so please feel free to edit.

lire originates from legō, whose active present infinitive is legere.

rire originates from rīdeō, whose active present infinitive is rīdēre.

  • 1
    Nothing explains it to us; theoretically it's the result of billions of uses over millions of speakers over a millennium or so, but in fact nobody was keeping track because everything was written in Latin. That's the way facts are -- they just are, and explanations if any come much later.
    – jlawler
    Aug 25, 2015 at 2:31
  • The -u ending of many past participles in French seems to be of uncertain etymology: books.google.com/… Aug 25, 2015 at 6:30
  • @sumelic Thanks. Which form do you mean by past participle? Please edit my post.
    – user5306
    Aug 25, 2015 at 15:19
  • The past participle (also called supine, though that name refers a different construction using the same verb-form) is the fourth Latin principal part (lego, legere, lexi, lectum), with a *-to suffix from PIE, like the cognate Greek "to-participle". In English the past participle is the third principal part (go, went, gone). You can look them up yourself; that's why dictionaries give principal parts. English often borrows different words from different verb forms of the same verb, like sum, essence, and future, all from the same Latin verb.
    – jlawler
    Aug 25, 2015 at 17:22
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    @jlawler. Do you really think English "sum" (as in "sum total") is borrowed from Latim "sum" ("I am")?
    – fdb
    Aug 25, 2015 at 18:14

1 Answer 1


First of all: I want to say that this question is not at all bad.

In Latin, lego, legere, lēgī, lēctus “to read” belongs to the third conjugation, while rīdeo, ridēre, rīsī, rīsus “to laugh” belongs to the second conjugation. As you can see, they are completely different in each of the four principal parts. So it is not so much a question of similar verbs developing differently as of very different verbs becoming more similar. Languages work in both ways.

Latin had a fair number of verbs with a perfect participle in –ūtus, for example secūtus from sequor “to follow”. In Romance languages this form has spread to a large number of different verbs, including French venu, Italian venuto, where it replaced the ending of Latin ventus, but this has not by any means happened to all verbs. For example, it affected lego, but not rīdeo.

  • Note that both lectus and ventus have that CC cluster you can put additional vowels in but with risus, not so much (there would have to be some crazy transient form like ridutus).
    – Eleshar
    Jun 26, 2017 at 23:08
  • Hmm, is a Vulgar –ūtus form really the explanation for the lu form in French? In Italian, the past participle of leggere is letto, directly from Latin lectum, although I don't know if that could be a more learned form that ultimately replaced a popular *leggiuto.
    – LjL
    Feb 9, 2019 at 21:31

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