Portuguese has a strange coincidence in the preterit perfect tense of the verbs ir (to go) and ser (to be): they are conjugated exactly equally.

Portuguese — English to go | English to be

  • Eu fui — I went | was
  • Tu foste — You (singular) went | were
  • Ele/Ela foi — He/She went | was

  • Nós fomos — We went | were

  • Vós fostes — You (formal / plural (outdated)) went | were
  • Eles/Elas foram — They (masculine/feminine) went | were

What is the name of this verb conjugation convergence phenomenon? Do you know more examples of it occurring in any language?

  • I don't understand your question. Do you mean that the two verbs have exactly the same forms for this tense?
    – curiousdannii
    Sep 10, 2014 at 1:01
  • 2
    Same thing in Spanish. The preterite (old Latin perfect) forms of both ser and ir are: fui, fuiste, fue, fuimos, fueron. The perfect of ire (ii, iiste, ivit,) must have died out, and the perfect form of esse (fui, fuiste, fuit,_) took over.
    – jlawler
    Sep 10, 2014 at 2:26
  • @curiousdannii: Yes, it is exactly that.
    – sergiol
    Sep 10, 2014 at 8:29
  • 1
    @jlawler "in a different ablaut grade" -- not really; this PIE root appears only to have existed in the zero grade (*bhuH). Fio appears to be a derivative in -ye/o- (*bhUh-ye/o-).
    – TKR
    Jun 15, 2016 at 23:35
  • 1
    Other examples: Asturian has the ser/dir (to be/to go) overlap in preterite and derived forms, but also has tar/tener (to be/to have; tuvi, tuvisti...) sharing in preterite and derived. In the potential mood, dir/dicir (to go/to tell; diré, dirás...) also overlap. Jun 16, 2016 at 17:12

3 Answers 3


Corbett calls this (in Spanish) overlapping suppletion in his 2007 paper in Language. Stump is credited with the term heteroclisis (see Maiden (2009)).

  • 2
    "overlapping suppletion" could be translated to Portuguese with something as "Supletismo por sobreposição"
    – sergiol
    Sep 10, 2014 at 8:49

Corbett's 2007 paper attributes the term "overlapping suppletion" to Juge (1999). Juge, Matthew L. 1999. On the rise of suppletion in verbal paradigms. Berkeley Linguistics Society 25.183–94.


Another example in another language (English):

English "go" and "wend" share the same past, although Dictionary.com & Amer. Heritage say the past of "wend" is now "wended", and "went" is archaic:

I went; (thou wentest); he/she/it went; we went; you went; they went

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