Irritability (HP_0000737) is an emotional state characterized by negative feelings of heightened frustration, annoyance, or feeling upset, often triggered by internal factors (e.g., fatigue, hunger, unfulfilled desires) or external factors (e.g., social or environmental challenges). Irritability may be unpredictable, and is accompanied by a lowered threshold for emotional reactivity and observable features (speech, facial expressions, or psychomotor activity). Also known as: Cranky, Easily annoyed, Easily bothered, Easily upset, Grumpy, Hot-temper, Irritable, Irritable mood.