(informal)a difficult problem or question难题；棘手的问题see alsobrain-teaser
(also teaser ad)
an advertisement for a product that does not mention the name of the product or say much about it but is intended to make people interested and likely to pay attention to later advertisements前导广告，悬念式广告（含蓄而引人好奇）
For the first week we ran a teaser featuring a black cat.在第一周，我们运行了以黑猫为主题的预告片。