[jaclaz]

Only for the record, there must have been some issues in the English transposition, in Italian those are:

f - forte

ff - fortissimo

fff - fortissimissimo

ffff - fortissimissimissimo

https://it.wikipedia.org/wiki/Dinamica_(musica)#Segni_dinami...

(not that I know anything on music, fortississimo and fortissississimo didn't sound right to me and looked for them)

[scns]

Per the article, Mahler used fffff the old protorocker.