pervasive
Spreading everywhere and affecting almost everything around it.
Pervasive means spreading throughout something so completely that it's present everywhere, affecting or influencing almost everything. When something is pervasive, you can't escape it: it's woven into every part of a situation or place.
Think about how the smell of popcorn becomes pervasive in a movie theater, reaching every corner and hallway. Or consider how smartphones have become pervasive in modern life: you see them everywhere, on buses, in restaurants, at parks, fundamentally changing how people communicate and spend their time.
The word often describes things that spread gradually but thoroughly. A pervasive attitude of kindness in a classroom means almost everyone treats each other well, creating an atmosphere that shapes how students behave. A pervasive problem, like bullying in a school, affects many students across different grades and situations, making it harder to solve because it's not isolated to one place or group.
Pervasive can describe both positive and negative things. A pervasive sense of excitement might fill your house before a big family trip. A pervasive fog might blanket an entire valley. When something is truly pervasive, it has seeped into so many places that addressing it, changing it, or escaping it takes broad effort.