Doesn't the "yn" suggest an adverbial construction? "More wetly" or something?
Possibly, but as in English it wouldn't have much application in this particular case
gwlypach would be better for 'wetter' on its own. yn wlypach only really makes sense as part of a sentence. We will sort it out once Duo fix the zombie bug, and in the meantime I have added gwlypach as an option.
The important thing to notice here is the internal hardening of -b- to -p- - a common feature in creating some comparative adjectives from the basic form, and also in some other circumstances in Welsh.
[Internal hardening of sounds is a feature of the Gwentian dialect, as well.]
A usual initial soft mutation would be p- - b-, for example:
- Pwllheli, i Bwllheli - Pwllheli, to Pwllheli
But you will also sometimes meet mutations inside words when they are modified, perhaps when modifying adjectives to give equative, comparative and superlative endings. These changes often go the other way round to a soft mutation, so it is called 'hardening':
- gwlyb, gwlypach - wet, wetter (the -b has hardened to -p-)
- tlawd, tlotach - poor, poorer (-d to -t-)
Hardening is sometimes a general feature of the Gwentian dialect of SE Wales. You might hear, for example, rhag ofn (in case) pronounced as /rac ofon/, especially by older people.