pensaernïaeth

Welsh

From pen (“head, chief”) +‎ saernïaeth (“architecture, workmanship”).^[1]

(North Wales, standard, colloquial) IPA^(key): /ˌpɛnsaɨ̯rˈniː.aɨ̯θ/
- (North Wales, colloquial) IPA^(key): /ˌpɛnsɛrˈniː.ɛθ/
(South Wales, standard) IPA^(key): /ˌpɛnsai̯rˈniː.ai̯θ/
- (South Wales, colloquial) IPA^(key): /ˌpɛnsɛrˈniː.ɛθ/

Note the unusual pronunciation of the first ae as /aɨ̯, ai̯/ rather than expected /eɨ̯, ei̯/.

pensaernïaeth f (uncountable)

Welsh mutation
radical	soft	nasal	aspirate
pensaernïaeth	bensaernïaeth	mhensaernïaeth	phensaernïaeth
Note: Some of these forms may be hypothetical. Not every possible mutated form of every word actually occurs.

^ R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke et al., editors (1950–present), “pensaernïaeth”, in Geiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies