The fourth sound for this column is ze, which is written in hiragana as ぜ and katakana as ゼ.
Zekken (ゼッケン) is a racing number. It comes from the German word Decken. This only meets my common use rule if you are a cyclist, a runner, or you bet on the horses. For the rest of you, I’ll offer up another word.
Zemi (ゼミ) is commonly used to refer to a seminar. Just today, while researching this post, I discovered the reason why the word is zemi instead of semi. This also comes from German, hence the ‘z’ sound at the beginning. The words zeminaaru and seminaa are also acceptable, but they are used less often. You know the rule in language: the shorter word is better.
We had our annual physicals recently and I was involved in translating the health questionnaires. Just by chance a couple of good words started with ze.
Zeizei (ぜいぜい) is ‘wheeze’ or ‘whoop’.
Zensoku (ぜんそく) is ‘asthma’ and can also be written in kanji as 喘息. The kanji characters are not so difficult, but the first character is not in the standard use list, so this word is generally written in hiragana.