Alterity

Have you ever had an experience that was so surprising or strange that it challenged your whole way of thinking about something? Something that called your life into question? Something that demanded a radical response—a Yes or a No. For example, “Oh my God, yes, why didn’t I see that before!?” or “No bloody way that could be true!”
 
Such intrusions into your ways of thinking and being are called experiences of alterity.
 
Merriam-Webster defines alterity as ‘otherness’; “specifically: the quality or state of being radically alien to the conscious self or to a particular cultural orientation.”
 
Alterity, which first appears in English in the 1640s, comes from Middle English alterite (change, state of being changed; difference), Latin alteritas, and Latin alter (second, other; the other of two).
 
Latin alter has its origins in the Proto-Indo-European (PIE) root al-(1) meaning beyond. The English verb ‘to alter’, from the late 14th century, means to change something or to make something different in some way. Such a change is something which you did not see coming. It is a change that was beyond your awareness until it arrived in front of you.
 
Reference: Online Etymological Dictionary, https://www.etymonline.com/
https://www.merriam-webster.com/dictionary/alterity