What is the adverb of irritability?

There isn't a single, perfect adverb for "irritability". However, here are some options depending on the context:

Directly related to irritability:

* Irritably: This is the most direct adverb, meaning "in an irritable manner." Example: "He spoke irritably about the delay."

* Impatiently: This implies a feeling of annoyance at being delayed or hindered. Example: "She waited impatiently for the bus."

Related to the effect of irritability:

* Angrily: This expresses strong anger, often stemming from irritability. Example: "He yelled angrily at the customer."

* Frustratedly: This conveys a sense of being blocked or hindered, often due to irritability. Example: "He threw the book down frustratedly."

* Snappishly: This implies a short, sharp, and irritable response. Example: "She answered snappishly when asked about her day."

The best choice depends on the specific situation and the nuance you want to convey.