#Backstory

*Diezmar* is a more modern version of *dezmar*, meaning "to decimate".

Many verbs undergo diphthongization in their conjugations when stressed syllables fall on historic vowels `/ɛ/` `/ɔ/` from Latin<sup>0</sup>.

e.g. 

- *p**e**nsar* > *p**ie**nso*
- *p**o**der* > *p**ue**do*

But I can think of no other examples where this diphthongization carries on into the (unstressed position) in the infinitive (and thus *all* conjugated forms).

The *RAE* [claims](http://dle.rae.es/?id=DitQLZk) the addition of the diphthong is due to the influence of (the noun) *diezmo*:

>###[diezmar](http://dle.rae.es/?id=DitQLZk)
De *dezmar*, **por infl. de *diezmo*.**

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#Question

Are there any other examples of verbs which have changed their form under the influence of a noun cognate? And if not, why did it happen with this verb?

e.g.

- *dezmar* > _d**ie**zmar_ (por inf. de *d**ie**zmo*)
- *pensar* > _*p**ie**nsar_ (por inf. de *p**ie**nso*<sup>3</sup>)
- *contar* > _*c**ue**ntar_ (por inf. de *c**ue**nto*)


**Note:** I am not looking for instances of verbs which have diphthongs due to the Latin root having two neighbouring vowels e.g. *or**ie**ntar* from Latin *or**iē**ns*<sup>4</sup>.

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##Extra info

Etymological history of relevant terms:

- `Latin` *decem* ("ten")
 - `Spanish` *diez* ("ten")
 - `Latin` *decĭmus* ("tenth")
     - `Old Spanish` *diezmo* ("tithe")
         - `Spanish` *diezmo* ("tithe")
     - `Latin` *decimāre* ("to decimate; to tithe")
         - `Spanish` *dezmar* ("to decimate; to tithe")
             - `Spanish` *diezmar* ("to decimate; to tithe")

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[Google Ngrams](https://books.google.com/ngrams/graph?content=diezmar%2Cdezmar&year_start=1600&year_end=2000&corpus=21) comparison of *diezmar*<sup>1</sup> and *dezmar*<sup>2</sup>.

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##Notes:  

<sup>**0.** https://linguistics.stackexchange.com/a/20696/20700</sup>

<sup>**1.** earliest example: 1728</sup>

<sup>**2.** earliest example: 1610</sup>

<sup>**3.** Meaning #2 - http://dle.rae.es/?id=SxBPv3A|SxCsyei</sup>

<sup>**4** [Diccionario Crítico Etimológico Castellano E Hispánico](https://www.scribd.com/document/158436269/Diccionario-Critico-Etimologico-castellano-MI-RI-Corominas-Joan-pdf), Joan Corominas</sup>

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**EDIT:** Creating a list of examples from the answers:

- *dezmar, diezmar* (*diezmo*)
- *amoblar, amueblar* (*mueble*)
- *[pontear](http://dle.rae.es/?id=TeHEvwQ), puentear* (*puente*)
- *festejar, fiestear* (*fiesta*)
- *-, afiebrarse* (*fiebre*)
- *-, cuerdear* (*cuerda*)

Extra:

- *cerner*, *cernir*
- *hender*, *hendir*
- *ergir* (*yer-*), *ergir* (*ir-*)
- http://conjugator.reverso.net/conjugation-verbs-with-double-participles-spanish.html
- [Spanish Verbs Made Simple(r) - By David Brodsky](https://books.google.co.uk/books?id=bUW7fa6oCb4C&pg=PA278&dq=alternative) (Search *"alternative"*)