When we talk about something being "by the curb," we mean that it is located near the edge of a sidewalk or road. This term can be easily substituted with other words depending on the context of the sentence. For example, you could say "beside the curb" or "along the curb" if you want to focus on the proximity of the object to the curb. Other synonyms include "adjacent to the curb" or "near the roadside." In some cases, "by the edge of the pavement" or "at the curb's edge" might be more appropriate. These synonyms can help to provide more descriptive language and make your writing more interesting and engaging.