snoop·er \-pə(r)\noun (-s) Etymology:snoop (I) + -er : one that snoops: as a.: a prying meddler b.: one employed as an inspector, investigator, detective, or spy < a wartime censor — one of the 15,000 snoopers who … opened your mail — Mary Knight > < an increased number of snoopers dogging him — Joseph Wechsberg > c.: an airplane working alone to search out, observe, and sometimes attack targets