This is the 5115th most frequent German word.
argen
"Argen" is an archaic German word meaning "to harm" or "to do mischief."
The word 'argem' here functions as an adjective describing the level of suspicion.
Er begegnete ihr mit argem Verdacht.
He approached her with severe suspicion.
In this sentence, 'arg' is used as an adjective to express how grave the situation is.
Die Lage war äußerst arg.
The situation was extremely dire.
Here, 'argte' is a verb form derived from 'argen,' showing an action taken concerning annoyance.