Ostracize comes from the Greek word ostrakizein, from ostrakon ‘shell or potsherd’ (on which names were written in voting to banish unpopular citizens).  

The word "ostracize" first appeared in English in 1649, in a poetic elegy by Andrew Marvell, borrowing from the Greek practice of banishing citizens by voting on potsherds. 

Examples of ostracize in a sentence: 
*She was ostracize from the scientific community for many years because of her radical political beliefs. 
*He was ostracized from the group - no one would reply to his emails and was not invited to meetings.  When he did attend, his comments and opinions were ignored and eye contact was avoided. 
*Lepers were ostracized from their community, due to the belief that the disease was contagious. 

The Black List in Hollywood during the 1940s and 1950s was a method of ostracizing actors for their suspected communist sympathies.  

Galileo was ostracized because he dared to publicly disagree with the church's view that the earth was the center of the solar system. 

Alan Turing, the father of modern computing and the man who solved the German Enigma machine, was persecuted and ostracized because he was a homosexual, as was the writer Oscar Wilde.