Testy (adjective)

1. Irritable; easily annoyed.
2. Short-tempered; quick to take offense.

Origin:

From middle english testif, from old french testif, testifs ("testy, irritable"), from latin testis ("witnes.s")

Examples:

1. The customer became testy when the salesperson couldn't answer his question.
2. The professor grew testy when the students didn't understand the material.
3. The testy tone of the conversation made it hard to have a productive meeting.
4. The testy exchange between the two politicians was broadcasted on TV.
5. The testy waiter was not pleasant to deal with.