Compacter has a few synonyms that can be used as an alternative depending on the context of the sentence. For instance, if you're talking about compacting soil or waste, the word compactor could be replaced by the terms tamper, compress, press, or crush. Additionally, if compact refers to a small and tightly packed space, then alternative words could include cramped, snug, or confined. If it refers to something smaller in size, then concise, condensed, or abbreviated could be used. Finally, for a dense, tough material, the words consolidated or solidified could replace compacter. It's always important to consider the context and meaning of the sentence when choosing a synonym.