"No thanks"

Translation: Dim diolch

[joviehavard]

What is the difference between dim and ddim? No vs. not?

[EllisVaughan]

No, "ddim" is the mutated form of "dim". Dim has a few meanings.

[AnUnicorn]

I thought you used nac or naddo when using "no" as an interjection, and (d)dim was more like "do not" (Dw i ddim yn hoffi...="I do not like...")?

[ibisc]

Just learn this one as an idiom without trying to break it down - dim diolch = no thanks. Word for word translations between Welsh and English are sometimes not very useful.

The mutated form ddim is used as a negative adverb ('not') with negative verbs - for example, rwyt ti (you are); dwyt ti ddim (you are not).