Where does “Llydawaidd” come from?

Llydawaidd (Welsh) comes from Welsh Llydaw, from Old Welsh Litau, from Proto-Brythonic llɨdaw, from Proto-Celtic ɸlitawyā, from Proto-Indo-European pelh₂k- — to spread out flat.

Ancestry of “Llydawaidd”, step by step

StepLanguageWordMeaning
1WelshLlydawBrittany
2Old WelshLitau—
3Proto-Brythonicllɨdawcontinent, mainland; Brittany
4Proto-Celticɸlitawyācontinent
5Proto-Indo-Europeanpelh₂k-to spread out flat
Every word from Proto-Indo-European pelh₂k- →Every word from Proto-Celtic ɸlitawyā →Every word from Proto-Brythonic llɨdaw →