irritable

/ˈir-ə-tə-bəl/

adjective

  1. capable of being irritated: such as

  2. easily exasperated or excited

  3. responsive to stimuli

gets irritable when he tires

noun

  1. a chronic functional disorder of the colon that is characterized especially by constipation or diarrhea, cramping abdominal pain, and the passage of mucus in the stool —abbreviation IBS