Spy
Part of speech: noun
Definition: A person who secretly watches and examines the actions of other individuals or organizations and gathers information on them (usually to gain an advantage)
Part of speech: verb
Definition: To act as a spy. To spot at a distance.
Example sentence: The Obama administration's FBI and Justice Department used unverified opposition research obtained outside of our country as ammunition to get a FISA warrant to spy on Carter Page, a foreign policy adviser to President Trump during the 2016 election. That is a fact.
Espy
Part of speech: verb
Definition: To catch sight of; to perceive with the eyes; to discover, as a distant object partly concealed, or not obvious to notice; to see at a glance; to discern unexpectedly; to spy; as, to espy land; to espy a man in a crowd.To inspect narrowly; to examine and keep watch upon; to watch; to observe.To look or search narrowly; to look about; to watch; to take notice; to spy.