apocope
Concise Oxford English Dictionary © 2008 Oxford University Press:
apocope /əˈpɒkəpi/
▶noun Linguistics omission of the final sound of a word, as when cup of tea is pronounced as cuppa tea.
– origin C16: from late L., from Gk apokoptein ‘cut off’.
'apocope' also found in these Oxford entries:

