The term 'appear or become visible' can be described by four different words: EMERGE (6 letters), SEEM (4 letters), LOOM (4 letters), and RISE (4 letters). EMERGE means to come out of a state of obscurity or seclusion, while SEEM implies that something is visible but not necessarily tangible. LOOM is used to describe something that appears suddenly and unexpectedly, and RISE is used to describe something that gradually becomes visible. All four words are used to describe the same concept of something appearing or becoming visible.