The expression "was naive" can be replaced with several alternative phrases or synonymic appraisals. One could say "was innocent," "was inexperienced," "lacked sophistication," "had a childlike understanding," or "was gullible." Other synonyms could include "unworldly," "impressionable," "unsuspecting," "credulous," "green," or "naive." These terms all describe someone who lacks practical experience or discernment and is therefore easily deceived or misled. It's not necessarily a negative trait, as naivete can be endearing. However, it can also lead to vulnerabilities that might be exploited. Hence, it is necessary to be aware of synonyms for the expression and understand their implications.