The spelling of the word "ducis" is based on its phonetic pronunciation. The IPA phonetic transcription of the word is /ˈdjuːsɪs/. The initial sound /d/ is phonetically spelled with the letter "d", followed by the vowel sound /uː/ spelled with the letters "u" and "c". The final sound /sɪs/ is represented by the letters "s" and "i". Therefore, the correct spelling of the word is "ducis", which is pronounced as "doo-sis".
The word ducis is Latin in origin. It is the genitive form of the Latin noun dux, which translates to leader or guide. The etymology of dux can be traced back to the Latin verb ducere, meaning to lead or to take.