Crossers is a relatively uncommon word that means someone who crosses or passes over something, such as a bridge, road, or boundary. If you're looking for synonyms for this term, there are a lot of options depending on the context. If you're talking about people who cross a border, you might use words like migrants, refugees, or unauthorized immigrants. For someone who crosses a road, you could say pedestrian, walker, or crosswalk user. If you're referring to someone who crosses a river or body of water, you could use words like swimmer, boater, or kayaker. Other potential synonyms might include traveler, trekker, hiker, or adventurer.