-EU | |||
| adeilad | adeiladeu | buildings | |
| cerdd | cerddeu | poems, songs | |
| cleddyf | cleddyfeu | swords | |
| clust | clusteu | ears | |
| hundy | hundyeu | bedrooms | |
| yneuadd | yneuaddeu | halls | |
(with vowel change) | |||
| bwrdd | borddeu | tables | |
| hebawg | hebogeu | falcons | |
| tlws | tlyseu | jewels | |
-ON, -ION | |||
| coch | cochion | red | |
| cydymdeith | cydymdeithon | companions | |
(with vowel change) | |||
| gwas | gweison, gweision | servants, fellows | |
-OEDD | |||
| llys | llysoedd | courts | |
| ynifer | yniferoedd | retinues | |
-I | |||
| llestr | llestri | dishes, vessels | |
Vowel Change (an original -I disappeared and left an affection) | |||
| gwr | gwyr | men | |
| gwrda | gwyrda | goodmen | |
| ieuanc | ieueinc | young | |
| march | meirch | horses | |
| ystafell | ystefyll | rooms | |
Irregular | |||
| ci | cwn | dogs | |
| helgi | helgwn | hunting-dogs | |
| milgi | milgwn | greyhounds | |

All text copyright © 1996 by Gareth Morgan. Online layout copyright © 2001 by Daniel Morgan.