Irritable is the mood where everything is too much. The dog barking, the kettle taking its time, someone asking a completely ordinary question — an irritable person snaps at all of it. Hungry, short of sleep, three days into a cold: that is when it turns up.
It works as a passing state and as a whole character: an irritable man, or simply irritable this morning. The noun is irritability and the adverb is irritably — he answered irritably, without looking up from the paper. Medicine borrows the word for bodies instead of moods, as in irritable bowel syndrome, where the gut reacts to what it should ignore. Keep it apart from irritating: the thing that annoys is irritating, the person it annoys is irritable. Swap those round and you have accidentally called yourself the problem.
1adjectiveirritableEasily annoyed; quick to lose patience over small things.
“He gets irritable when he skips lunch.”
2adjectivebodyOf a body part: reacting strongly and painfully to things that should cause no reaction.
“She was diagnosed with irritable bowel syndrome in her twenties.”
Also accepted in games: grumpy, cranky
Irritable came into English through French irritable, which had it from Latin irritabilis, able to be provoked. English kept both halves of that idea: a person you can provoke with almost nothing, and a body that reacts to what should not bother it at all.
Latin
irritabilis
French
irritable
English, today
irritable
Borrowed from French irritable, from Latin irritabilis.
Etymology from Wiktionary, CC BY-SA