easily irritated or annoyed; "an incorrigibly fractious young man"; "not the least nettlesome of his countrymen"
If you are irritable, you are easily annoyed. He had been waiting for over an hour and was beginning to feel irritable. + irritably ir·ri·tably `Why are you whispering?' he asked irritably + irritability ir·ri·tabil·ity Patients usually suffer from increased irritability. getting annoyed quickly or easily = crabby