Seater is a word that is commonly used to describe seating capacity in vehicles or at venues. However, there are other synonyms that can be used to describe the same thing. For instance, the word 'occupant' refers to someone who is seated in a particular place. The word 'passenger' is commonly used in the context of travel. Another synonym for seater is the word 'bench,' which is commonly used in the context of parks or public transportation. Finally, the word 'situated' can also be used to describe the location or position of seats in a venue or stadium. All of these words provide alternatives to the word 'seater' when describing seating capacity or location.