"In absentia" is a phrase used to describe an action or event that occurs in someone's absence. However, there are various synonyms that can be used instead of this phrase depending on the context. For example, the phrase can be replaced with "in her/his absence" or "in their absence." Similarly, "without attendance" or "without a presence" can be used to convey the same meaning. Additionally, "posthumously" can be used when referring to someone who has passed away, but an action is being taken on their behalf after their death. Whatever the context, these synonyms add variety to the language and can help to convey information more effectively.