Early 19th century; earliest use found in Philosophical Transactions of the Royal Society of London. From electro- + dynamical, probably after French électro-dynamique.
Definition of electrodynamical in US English:
electrodynamical
adjectiveɪˌlɛktrəʊdʌɪˌnamɪkl
Physics
Electrodynamic.
Origin
Early 19th century; earliest use found in Philosophical Transactions of the Royal Society of London. From electro- + dynamical, probably after French électro-dynamique.