The phrase "hard by" is an idiomatic expression that means "nearby" or "close to." There are numerous synonyms for "hard by" that can be used to convey the same meaning. Some of these synonyms include "adjacent to," "near," "beside," "next to," "alongside," "by," and "close by." These words can be used interchangeably in sentences to substitute for "hard by." For instance, "The store is hard by the gas station" can be rephrased as "The store is adjacent to the gas station." Each of these synonyms has its own subtle nuances, but they all convey the same general meaning of being in close proximity.