Noun

• S: (n) staining, spotting, maculation (the act of spotting or staining something)
• S: (n) detection, catching, espial, spying, spotting (the act of detecting something; catching sight of something)

Verb

• S: (v) descry, spot, espy, spy (catch sight of)
• S: (v) spot, recognize, recognise, distinguish, discern, pick out, make out, tell apart (detect with the senses) "The fleeing convicts were picked out of the darkness by the watchful prison guards"; "I can't make out the faces in this photograph"
• S: (v) blemish, spot (mar or impair with a flaw) "her face was blemished"
• S: (v) spot, fleck, blob, blot (make a spot or mark onto) "The wine spotted the tablecloth"
• S: (v) spot (become spotted) "This dress spots quickly"
• S: (v) spot (mark with a spot or spots so as to allow easy recognition) "spot the areas that one should clearly identify"