Real Dictionary

trend
To set a trend means to do something that becomes accepted or fashionable, and that a lot of other people copy.
countable noun: A trend is a change or development towards something new or different.
verb: If something such as a topic or name is trending, a lot of people are discussing or mentioning it on social media.

trend in American English
to extend, turn, incline, bend, etc. in a specific direction; tend; run
intransitive verb: to have a general tendency, as events, conditions, etc
noun: the general course or prevailing tendency; drift

trend in British English
to take a certain trend
noun: general tendency or direction