What is Angst? In one word -- angst is Liason. But according to Wikipedia, Angst is...

a German word for fear or anxiety. (Anguish is its almost entirely synonymous latinate equivalent.) It is used in English to describe an intense feeling of emotional strife. In German, it is the fear of possible suffering and a behavior resulting from uncertainty and strain which is caused by pain, loss, and death. The term Angst distinguishes itself from the word Furcht (German for "fear") in that Furcht usually refers to a material threat (arranged fear), while Angst is usually a nondirectional emotion. However, today Furcht is rarely, if ever, used^{[citation needed]}, and fear of [...] is expressed as Angst vor [...].

In other languages having the meaning of the Latin word anxietas and pavor, the derived words differ in meaning, e.g as in the French anxieté and peur.

The word Angst has existed since the 8th century, coming from the base-Indoeuropean *anghu-, "restraint" from which Old High German angust develops. It is pre-cognate with the Latin angustia, "tensity, tightness" and angor, "choking, clogging"; compare to the Greek "άγχος" (ankhos): stress.