Does the Spanish word onerous mean expensive?

No, "onerous" in Spanish is not the same as "expensive". While they can sometimes be related, they have different meanings:

* Oneroso: This word translates to burdensome or heavy. It refers to something that is difficult, demanding, or oppressive, usually in a metaphorical sense. For example, "un trabajo oneroso" would mean "a burdensome job".

* Caro: This is the Spanish word for expensive. It refers to something that has a high price.

While an expensive item can be burdensome to purchase, the words themselves are not interchangeable. "Oneroso" focuses on the difficulty or strain something creates, whereas "caro" focuses on the cost.