To all seeming means something appears to be a certain way, but the reality may be different. Synonyms for the phrase include seemingly, apparently, ostensibly, outwardly, and superficially. These words all convey a sense of outward appearance that may not reflect the true nature of the situation. Other similar terms include at first glance, on the face of it, and to appearances. These phrases can be useful for describing situations where something appears to be one way but may warrant a closer examination to uncover the truth. Ultimately, when using synonyms for to all seeming, it's important to be aware of the connotations and nuances of each term to use it effectively.