File under "words that need to enter my actively-used vocabulary, and fast": Butyraceous. Here's all you need to know:
BUTYRACEOUS. bu·tyr·a·ceous - adjective
Pronounce it: byoo-tuh-rey-shuhs
Meaning: Of, containing, or resembling butter.
Use it in a sentence (with thanks to a clever comment here): Upon tasting the creamy topping on his toast, Fabio exclaimed, "I can't believe it's not butyraceous."