No, "Y dewr" or "Y ddewr" would be "The brave" (Note no mutation if it's for a man, but there is a mutation for a women: At least I'm fairly certain about this).
Many Welsh adjectives can also be used as nouns, generally in the plural form (if one exists).
- tlawd, tlodion, y tlodion - poor, poor people, the poor
- cyfoethog, y cyfoethogion - rich, the rich
- glas, gleision, y Gleision - blue, freshers (in a university, for example), the Blues (a Welsh rugby team)
- enwog, yr enwogion - famous, the famous/renowned (as in the national anthem - ...enwogion o fri)
If you wanted to say something like 'the brave one' then you could use yr un dewr/ddewr (ddewr for a female)
And a number of similar meanings - look up dewr in a dictionary or thesaurus. 'Brave' is a common one, though.
We don't give all possible meanings of words on this course as everything has to be entered manually.