A coined word is a newly invented term or word, commonly referred to as a neologism. It can also be an already existing expression or phrase used in a different sense. Neologism is derived from the Greek words neo, which means new and logos, which means speech or utterance.
Coined words or neologisms are introduced by a specific person, publication, period or event. An author who used a fresh word in his book is presenting that term to the public. If the readers accepted that specific word into normal language, it will then be part of daily conversations and regular use.