anger (n.)

mid-13c., "hostile attitude, ill will, surliness" (also "distress, suffering; anguish, agony," a sense now obsolete), from Old Norse angr "distress, grief, sorrow, affliction," from Proto-Germanic *angaz (from PIE root *angh- "tight, painfully constricted, painful"). Cognate with German Angst. Sense of "rage, wrath" is early 14c. Old Norse also had angr-gapi "rash, foolish person;" angr-lauss "free from care;" angr-lyndi "sadness, low spirits."

anger (v.)

c. 1200, "to irritate, annoy, provoke," from Old Norse angra "to grieve, vex, distress; to be vexed at, take offense with," from Proto-Germanic *angaz (source also of Old English enge "narrow, painful," Middle Dutch enghe, Gothic aggwus "narrow"), from PIE *anghos, suffixed form of root *angh- "tight, painfully constricted, painful."

In Middle English, also of physical pain. Meaning "excite to wrath, make angry" is from late 14c. Related: Angered; angering.