The North Wales version is 'ei daldra o'.
You may be referring to 'uchder' which means the height of a thing, eg a mountain.
The only correct word for height of a person is 'taldra' and its mutated forms 'fy nhaldra i', 'dy daldra di' etc.
I submitted ei daldra o on previous exercise and was marked incorrect. No option to report incorrect answer on "report a problem" tab
taldra - height of something, as in a physical property
uchder - altitude or elevation, as in geography.
uchder does sometimes get used for the physical property, but taldra is the more specific word for that.
Yes. Both -dra and -der are noun suffixes, so if you are using an e-dictionary that allows wildcards you can easily find other examples where they are used to create nouns from, say, adjectives. There are many other suffixes and prefixes which create various common meanings and functions.