/ˈtiːzər/
teaser
BrE /ˈtiːzə(r)/
NAmE /ˈtiːzər/
(informal)
a difficult problem or question
➡ see also brain-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