This word is the adjective for syphilis, a serious disease that passes from person to person during sex. Syphilis is caused by a bacterium, and if nobody treats it, it stays in the body for years and slowly damages the heart, the brain and the nerves. Today it can be cured with antibiotics, but before that medicine existed it ruined and ended many lives, so the word carries a heavy, old feeling. 'Syphilitic' is used two ways. Most often it describes something belonging to the disease: a syphilitic infection, a syphilitic sore, syphilitic damage to the brain. Less often it describes a person who has the disease — and you can also say 'a syphilitic' as a noun, meaning a person with syphilis. That noun use sounds cold and old-fashioned now, the way a doctor a hundred years ago might have written in a file; today people say 'a patient with syphilis' instead, because naming someone by their illness feels unkind. This is a medical word, not a conversation word. You will meet it in medical writing, in history books, and in novels set in the past — writers love it because syphilis was common among artists and soldiers in the 1800s. Note also that in angry old-fashioned insults, English speakers sometimes threw 'syphilitic' at someone with no medical meaning at all, just as a filthy insult; you should recognise this but never use it.

梅毒的；梅毒患者。台灣醫學用語就是「梅毒」，「syphilitic」是它的形容詞形式，例如「梅毒性潰瘍」「梅毒性心臟病」。注意：中文的「梅」跟梅子、梅花沒有關係，這個名字來自古時候對皮膚疹子形狀的描述，別被字面誤導。