Navvies, which is a colloquial term for workers involved in the construction of railway lines and canals, can also be referred to by a variety of synonyms. Some of these synonyms include laborers, construction workers, builders, excavators, and diggers. Additionally, the term "navvy" typically refers to manual labor jobs that require hard physical work and long hours. Synonyms that convey this connotation include grunt workers, toilers, and heavy lifters. Other possible synonyms for navvies include road workers, civil engineers, and construction crews. However, the specific implication of each synonym may vary, so it is important to consider the context before using any alternative terms.