This is the 1426th most frequent German word.
krankheit
Illness or disease.
Here, 'Krankheit' is used to describe a general medical condition or illness in a broad sense.
Die Krankheit breitet sich schnell aus.
The illness is spreading quickly.
In this sentence, 'Krankheit' refers to the concept of illness in a general scientific or medical context.
Eine Krankheit kann durch Viren verursacht werden.
An illness can be caused by viruses.
In this case, 'Krankheit' is used to refer to a past specific period of illness experienced by an individual.