Duden defines shitstorm as: ‘Noun, masculine – a storm of protest in a communications medium of the internet, which is associated in part with insulting remarks.’ The entry in Duden of course is not in English, but rather reads: Substantiv, maskulin – Sturm der Entrüstung in einem Kommunikationsmedium des Internets, der zum Teil mit beleidigenden Äußerungen einhergeht Philip Oltermann gives some additional cross-cultural background ("A shitstorm in a dictionary", The Guardian 7/3/2013): The announcement that the word "shitstorm" has entered the most commonly used German dictionary, the Duden, after being used by Angela Merkel has triggered the usual wave of cliches: that Germans are darkly obsessed with pooping, farting and bottoms, psychologically stuck at the anally retentive stage.
Němčina má nové slovo, kvůli krizi zdomácnělo", iDNES.cz; "Duitsers omarmen Engelse shitstorm", NOS OP 3; "H αγγλική βρισιά shitstorm μπήκε στα λεξικά της γερμανικής γλώσσας -Τη χρησιμοποιεί και η Μέρκελ", iefimerida; "Shitstorm entra no diccionário alemão depois de usada por Merkel na crise", Diário Digital; "La langue allemande officialise l'anglicisme'shitstorm '", ActualLitté; etc.