anxiety n.

1520s, "apprehension caused by danger, misfortune, or error, uneasiness of mind respecting some uncertainty, a restless dread of some evil," from Latin anxietatem (nominative anxietas) "anguish, anxiety, solicitude," noun of quality from anxius "uneasy, troubled in mind" (see anxious).

It was sometimes considered a pathological condition (1660s); modern psychiatric use dates to 1904. Age of Anxiety is from Auden's poem (1947). For "anxiety, distress," Old English had angsumnes, Middle English anxumnesse.