I wonder if there'll be agreement on 'irony'. In British English, the ironic happening must necessarily be unintentional. It doesn't have to be unknown, just go against the intentions of the act (eg: an anticrime bill that the beat police know will raise crime)

In contrast, Americans often use 'irony' in an intentional manner. Selecting an ironic t-shirt to wear. Or the phrase that clued me into this: "The photographer has arranged the model's foot ironically".