Spy upon
To observe and spy upon are semantically related. In some cases you can replace phrase "To observe" with "Spy upon", this terms are similar.
To observe
Spy upon and to observe are semantically related. You can use "Spy upon" instead a verb phrase "To observe".
Mutual synonyms
Cite this Source
To observe and Spy upon. (2016). Retrieved 2026, August 02, from https://thesaurus.plus/related/spy_upon/to_observe
Spy upon & To observe. N.p., 2016. Web. 02 Aug. 2026. <https://thesaurus.plus/related/spy_upon/to_observe>.
To observe or Spy upon. 2016. Accessed August 02, 2026. https://thesaurus.plus/related/spy_upon/to_observe.
Google Ngram Viewer shows how "spy upon" and "to observe" have occurred on timeline