What does “vachement” mean in French?

Vachement is one of the most common intensifiers in spoken French: vachement bien, vachement cher, vachement en retard. It just means “really” or “seriously”, and the cow buried inside it is invisible to native speakers. Register-wise it is casual but not rude — you would say it to a friend or a colleague, and write très or vraiment instead.

The animal has not vanished completely: vache still works as an adjective for “harsh” or “mean” (c’est vache, ce qu’il a dit), and vachement is recorded in the early 1900s meaning “nastily” before it settled into a neutral booster a couple of decades later.