There are many synonyms for the phrase "lose big" that can be used to describe a significant defeat or failure. Some of these synonyms include "suffer a major setback," "take a heavy blow," "experience a crushing defeat," "endure a devastating loss," "be severely beaten," "sustain a significant defeat," "face a substantial failure," "suffer a sizeable defeat," and "be handed a significant loss." These phrases can be used in a wide range of contexts, such as sports, business, and personal life, to describe a situation where a significant defeat or loss has occurred. Each phrase has its own nuances, and it is important to choose the right one to convey the right meaning.