The phrase "put someone at a loss" is commonly used to describe situations where one is confused, uncertain, or unable to make a decision due to a lack of information. There are several synonyms for this phrase that can be used to convey a similar or related meaning. These include phrases such as "leave someone perplexed," "confound someone," "throw someone off their game," "put someone in a bind," and "baffle someone." Each of these phrases captures the essence of being at a loss and can be used in various contexts to describe situations where one is unsure or confused.