The present, perfect, and participle stems1 of the verb struere are stru-, strux-, and struct-. The -s- in the perfect stem and the -t- in the participle stem are nothing unusual, but they seem to follow a consonant that is absent from the present stem, perhaps -c-, -g-, or -h-.

The situation is similar to, for example, trah-/trax-/tract- and dic-/dix-/dict-. A partial example with a -g- is tang-/tetig-/tact-, which could all naturally come from a single stem tag-. The thing I don't understand is why there is no consonant at the end of the present stem of struere.

Was there ever a consonant that was later dropped — was it struhere or strucere or something similar? If not, what explains the discrepancy between the present stem stru- and the two other stems? Or is this just an irregularity I should accept without explanation? I fail to see a story behind the paradigm stru-/strux-/struct-, although I can justify most Latin verb paradigms at least to myself. Any explanation about the background of the stems of struere would be welcome.

1 I don't know the canonical names of these stems, but that's tangential. I hope the terminology is clear enough. I prefer short names for fluency.

  • I've mostly heard them called the "first, second, and third" stems, or the "present, perfect, and participle" stems
    – Draconis
    Jun 25, 2017 at 4:13

2 Answers 2


The form structum seems to have "c" by analogy to stems that had labiovelar consonants in Proto-Indo-European, as Alex B. says.

In frūctus (from fruor) the Indo-European present stem ended in a labio-velar gʷ, but various analogies no doubt account for strūctus, flūxus, old flūctus, uīctum (from struo, fluo, uīuo) (Vox Latina, W. Sidney Allen, Second Edition, p. 69) (First published 1965, Second edition 1978)

There is also a relevant footnote on this page:

  1. Old Latin [for fīgo] is in fact fīuo, with u from Indo-European gʷ. But note nīxus (and nictare) from (co)nīveo, where u is from Indo-European gʷh.

In Perkins (1875) I found the following examples of verbs that have a velar consonant only in non-present stems:

  • fluo, fluxi, fluctum/fluxum
  • struo, struxi, structum
  • vivo, vixi, victum

(p 36)

  • fruor, fructus/fruitus
  • nitor, nisus/nixus

(p 37)

"Latin Verbs in -uo, -uere", by Oswald Szemerényi, says

Two [of the verbs ending in -uo, -uere] show in the perfect and the PPP a velar stem:

fluo -ere fluxī fluctum (later fluxus)
struo -ere struxī structum.

No doubt ... the same type is seen in

fruor fruī frūctus

(p. 11)

Wiktionary (accessed 24 June 2017) gives the following etymologies:

  • fluo: "From Proto-Italic *flowō" (cites De Vaan), "from Proto-Indo-European *bʰlewgʷ-, from *bʰlew-"
  • struo: "From Proto-Italic *strowō" (cites De Vaan) "with spurious c in struxī and structum"
  • vivo: "From Proto-Italic *gʷīwō [...] The x and c in vīxī and vīctum were introduced by analogy with other verbs." I left out what Wiktionary says about the Indo-European etymology because my understanding is that this is a somewhat troublesome root to analyze

  • fruor: "From the Proto-Indo-European *bʰruHg-" (De Vaan is listed in the "references" section, but there's no explicit citation and no Proto-Italic form given)

  • nitor: "From Proto-Indo-European *kneygʷʰ- (“to bend, to droop”). Cognate with nicō, connīveō, nictō"

As you might have noticed, Wiktionary, unlike Allen, doesn't write a macron on structum, and there is a note in the Wiktionary entry for struo saying:

Please note that there is a disagreement over whether or not there is a macron on the third and fourth principal parts and the subsequent verb forms from these (strūxī for struxī and strūctum for structum).

However, there is no citation for this statement, so I don't know what the basis for the disagreement would be.

Bennett (1907) says

Gellius [...] testifies (Noctes Atticae, ix. 6) to the quantity of the vowels of āctus, lēctus, ūnctus, and in xii. 3. 4 to that of strūctus (p. 52)


the Romance languages [...] point to cīnxī, distīnxī, exstīnxī, fīnxī, pīnxī, strūxī, tīnxī, ūnxī (p. 53)

but perhaps there are some issues with this evidence, or opposing pieces of evidence. Bennet doesn't indicate any inscriptional evidence (e.g. use of the apex) for vowel length in this word.

Works cited

Further reading

Some links to further literature that seems relevant that I found by Googling, but that I haven't processed yet:

  • A side note. We know that eu > ū, so it's not quite clear why some (who?) speculate there was shortening in struxi or structum.
    – Alex B.
    Jun 25, 2017 at 3:18
  • @AlexB.: I'm also confused by the statement in Wikipedia. But perhaps the thought is that, since it was an analogical form, it might have assimilated to the form of words like ductus with short "u" before "ct". Or maybe there is unconclusive evidence from other authors or from Romance reflexes
    – Asteroides
    Jun 25, 2017 at 3:25
  • let's see if TKR or fdb adds anything.
    – Alex B.
    Jun 25, 2017 at 4:43

A good question.

  • Assimilation (voice): * tagto > * takto. This is a common phenomenon, cf. scribo-scripsi, veho-vixi etc. (see e.g. Weiss, p. 188, I.1);

  • With dico, there's nothing unusual: diksi, dikto;

  • With struo: k was inserted there analogically. Verbs ending in a labiovelar (kw, gw) follow this pattern:

  1. "the labial element of a labiovelar is deleted before a consonant" (Weiss, p. 188)

coquo- coxi, unguo - unxi

  1. "Labial and velar stops are devoiced and deaspirated before a voiceless obstruent" (Weiss, p. 188) - in other words, our voice assimilation again:

unguo - unxi

fivo (i.e. figo) - fixi

fluo - fluxi

coniveo - conixi

(Examples taken from Tronskii 1960, pp. 260-261).

Remember that PIE *gw > Lat. u̯ (unless after a nasal).

So, this rule applied - by analogy - to some verbs without a labiovelar, e.g. vivo-vixi or struo-struxi.

cf. Weiss "[a]lterations caused by the differing outcomes of the voiced labiovelars in prevocalic and preconsonantal position would lead to an alternation -u̯-V ~ -kT-" (p. 441)

or Meiser 1998:

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