The spelling of the word "radusa" can be explained through its IPA phonetic transcription. The first sound is /r/, followed by the vowel sound /a/, which is pronounced as in "father". The third sound is the consonant cluster /dʒ/, pronounced as in "jungle". The final sound is another vowel sound, /u/, pronounced like "oo" in "boot". Therefore, the correct spelling of the word is "radusa", and its pronunciation is /rəˈduʒə/.
There doesn't seem to be any widely recognized etymology for the word "radusa" in English. It is possible that "radusa" may be derived from a particular language or have a specific meaning in a certain context. If you can provide more information about the origin or context of the word, I may be able to assist you further.