halitosis這個自來自於拉丁文的
halitus，這個字第一次出現是在1874年，意思是呼吸，不過比較強調呼氣的部分（breath, exhalation, steam, vapor）；它與拉丁文的
halare （意為呼吸，一樣是著重在呼氣的部分： to breathe, emit vapor）。而字尾
-osis 在
第二十三課（一）學過，是與疾病有關的字尾。一樣跟呼吸有關有個字尾
-pnea，它是由希臘文的
pnoia來的，意思也是呼吸（breath)，在
第二十五課（二）有學到。
The word "halitosis" was first appeared in 1874. Halitosis means "bad breath". The word is originated from Latin
halitus, meaning breath, exhalation, steam, vapor. It is related to
halare (to breath, emit vapor). There is a suffix "-pnea" also meaning breath and it is originated from Greek
pnoia (breath). We learn that in Lesson 25-2.
根據維基百科的資料，口臭是看牙醫的第三名的理由；第一名是蛀牙、第二名是牙齦問題；世界上大約有兩成的人有口臭的問題，使得任何可以消除口臭的東西（口香糖、breath mint）都大行其道。
According to Wikipedia, halitosis is the third most frequent reason for people to seek dental care, following tooth decay and gum disease. Because about 20% of the general population are reported to suffer from it to some degree, anything that claim to be able to reduce halitosis (chewing gum, breath mint) are quite popular.
並非所有自認為有口臭的人都有口臭的問題：大約有5-72％因口臭而求診的病患，在專業檢查時並沒有真正的口臭。真的有口臭的人，往往是在齦或舌頭背面的細菌造成的。其他10％是由鼻腔、鼻竇、咽喉、肺、食道、胃或其它地方疾病造成。
Not all who think they have halitosis really have it. Significant percentages (5–72%) of people who suspect that they have halitosis have been reported not to have genuine halitosis when examined by professionals. Most of the occasion of halitosis (about 90%) is caused by bacteria present below the gumline and on the back of the tongue. The remaining 10% could be resulted from disorders in the nasal cavity, sinuses, throat, lungs, esophagus, stomach or elsewhere.
參考文獻 References：
Wikipedia.
Halitosis.
Merriam-Webster Dictionary.
Online Etymology :
halitosis.
