Specter
A visible ghost or spirit
Suspicious
having or looking like something is wrong or someone is behaving wrongly
Retrospective
To look back on
Inspector
a person whose job is to look for things
Spectrum
the colors that can be seen in a rainbow
Conspicuous
very easy to see or notice
Specimen
A small amount or piece of something that can be looked upon or tested
Speculate
To look at something and make guesses about it
Spectacle
To look at a striking performance or display
Spectator
person who looks at a show, game, or other events.