Motioner is a term used to describe someone who initiates or proposes a motion, idea or action in a group or organization. However, if you are looking for other synonyms that can be used in place of the term motioner, you can consider using words such as initiator, proposer, instigator, originator, starter, or founder. Other terms that can be used in some contexts include catalyst, prime mover, or generator. Whatever word you use, ensure that it fits the context and meaning you intend to convey and is understood by your audience. Each synonym has a slightly different nuance, so choose the word that best communicates what you want to say.