"Frightener" is a word that's often used to describe something or someone that elicits fear or dread in others. However, there are several synonyms for "frightener" that can be used depending on the context. These include "terrorizer," "haunter," "menacer," "scarer," "panicker," and "alarmist." Each of these words carries a slightly different connotation and could be used to describe a different kind of frightening experience. For example, "haunter" might be used to describe a ghost that frightens people, while "scarer" might describe a person dressed up in a scary costume to jump out and frighten others. Ultimately, the choice of synonym will depend on the specific situation and the tone desired.