A fad¹ is any form of behavior that develops among a large population and is collectively followed with enthusiasm for some period, generally as a result of the behavior's being perceived as novel in some way. A fad is said to "catch on" when the number of people adopting it begins to increase rapidly. The behavior will normally fade quickly once the perception of novelty is gone.

 

Fad指因其新奇性而在一段时间内被广泛普及并受到人们追捧的某种行为，我们称之为“昙花一现的潮流”。当追随这一潮流的人数迅速增加的时候，我们就可以说这个潮流开始“流行”。通常来说，一旦其新奇性消失，这种潮流就会迅速消亡。

 

The specific nature of the behavior associated with a fad can be of any type including language usage, apparel, financial investment, and even food. Apart from general novelty, fads² may be driven by mass media programming, emotional excitement, peer pressure, or the desire of 'being hip³'.

 

可称为“昙花一现的潮流”的行为可以是任何形式的，包括语言的使用、服饰、金融投资，甚至食物。除其本身的新奇性之外，这些潮流也可能因为受到大众传媒节目、情绪激动、同伴压力或者“想要走在潮流前端”的愿望等因素影响而流行起来。

 

Though the term trend may be used interchangeably with fad, a fad is generally considered a fleeting⁴ behavior whereas a trend is considered to be a behavior that evolves into a relatively⁵ permanent change. (Source: Wikipedia)

 

虽然trend（潮流、趋势）一词可与fad互用，不过，fad通常指转瞬即逝的行为，而trend多指能够带来永久改变的一些趋势和行为。