When first seen is a phrase used to describe the initial observation of something or someone. There are several synonyms for this phrase, including upon first glance, at first sight, on first appearance, and upon initial inspection. In some cases, alternative phrases that convey a similar meaning include when initially viewed, upon preliminary examination, and at the outset. These synonyms are all useful for describing the first impression of something or someone, and can be used in a variety of contexts such as writing, conversation, or documentation. Choosing the right synonym can add depth and clarity to your description and help you convey your message more effectively.