Hastati were ancient Roman soldiers who fought in the front lines of battle. Some possible synonyms for the word "hastati" include "frontline troops," "infantry soldiers," or "pikemen." Another possible synonym is "spearman," as the hastati were known for their use of a particular type of spear called a hasta. Other synonyms might include "foot soldiers," "combatants," or simply "soldiers." Ultimately, the choice of synonym will depend on the context in which the word is being used and the effect that the writer or speaker wishes to create.