Etymology of muñeca
The etymology of muñeca is thus:
Old Spanish
monneca > munneca > Spanish
muñeca
In Old Spanish, ñ was written nn, but the sound was the same. There do exist occasional spelling variants with a single n from Old Spanish documents, but given these appear in free variation with the nn spelling by the same authors, we can assume they are errors/spelling variants/shorthand and not indicative of a different unpalatalised pronunciation:
Et la eſtrella q́ es ſobre la monneca del braço dieſtro dela figura dela ſénora que eſta en la ſiella aſſentada a poder ſobreſta piedra […]
Pero eſto ſera mas cóplida miente deſcendiendo ſobresta piedra la útud de figura de mano de oḿe dela múneca arriba. eſtádo abierta.
- c. 1250: Alfonso X, Lapidario, f. 2v.
Unfortunately, this doesn't shed much light on where the change in Tagalog and other languages2 originated.
From muñeca to manika: Sound change in Tagalog
While most Spanish loanwords to Tagalog with ñ are spelled correspondingly ny1:
- banyo (baño), panyo (paño), konyo (coño), espanyol (español)
- espanya (españa), senyas (seña), senyales (señale), kastanyas (castaña)
notice that in all of these the vowel following the /ɲ/ is /o/ or /a/.
By contrast, in muñeca the /ɲ/ is followed by /e/, a front vowel, which in Spanish loanwords to Tagalog is occasionally heightened further to /i/, e.g.:
- bandila (bandera), hibla (hebra), kumpisal (confesar), litrato (retrato), talino (talento), manika (muñeca) etc
My hypothesis is that the palatalisation of the 'n' over time got 'absorbed' into the /i/, this being an uncommon series of sounds in Tagalog. Something along the lines of:
/muˈɲeka/
> */maˈɲika/
> */maˈnjika/
> */maˈniːka/
> /maˈnika/
The existence of the alternate orthography manyika in Tagalog may suggest that it was at one point pronounced closer to the Spanish root, and that the sound change happened in the Tagalog word itself.
Notes:
1. Further, in loanwords with /nj/ this sequence also becomes a palatal nasal: matrimonyo (matrimonio), alemanya (alemania), britanya (britania)
2. Note that the Portuguese word boneca (again derived from Spanish muñeca) also depalatalises the /ɲ/, despite this phoneme existing in Portuguese.
Sources:
• A Comparison of the Phonemic Systems of Spanish and Tagalog, Antonio Quilis (p.248, 2.6: Nasal Phonemes)
• https://en.wikipedia.org/wiki/List_of_loanwords_in_Tagalog#Spanish
• Spanish loan-words in the Tagalog language, Jose Villa Panganiban