Vain pretensions are essentially false claims or exaggerated promises made by an individual. There are several synonyms that can be used to describe this act, such as ostentation, conceit, pomposity, boasting, and arrogance. These words all convey the idea of an individual making grandiose declarations about themselves or their abilities, without any real substance to back them up. Other synonyms for vain pretensions include showiness, pretentiousness, self-importance, and swagger. All in all, the use of these synonyms essentially means that an individual is engaging in unnecessary and false displays of superiority, which ultimately undermine their credibility and reputation.