IPA: /ˌɛlɛkˈtrɒnɪk/
KK: /ɪˌlɛk.trəˈtɒn.ɪk/
Relating to the spread of electrical activity through living tissue or cells without the need for repeated signals.
The electrotonic properties of the nerve cells allow for efficient signal transmission.
Electrotonic is formed from "electro-" (from Greek "ēlektron", meaning amber or electricity) and "tonic" (from Greek "tonikos", meaning relating to tension or tone). The word refers to something that relates to electrical tension or energy.
Think of 'electricity' ('electro-') and 'tension' ('tonic') to remember that 'electrotonic' relates to electrical energy or tension.