IPA: /ˈtɛstɪnəs/
KK: /ˈtɛstɪnəs/
The quality of being easily annoyed or irritable.
His testiness was evident when he snapped at his friends over a small mistake.
Testiness → It is formed from "testy" (from Middle English *testy*, meaning irritable or easily annoyed) and the suffix "-ness" (meaning the state or quality of). The word "testiness" refers to the state of being irritable or easily annoyed.
Think of someone who is 'irritable' ('testy') and how that describes their 'state' ('-ness') of being easily annoyed.