quatrefoil
Concise Oxford English Dictionary © 2008 Oxford University Press:
quatrefoil /ˈkatrəfɔɪl/
▶noun an ornamental design of four lobes or leaves, resembling a flower or clover leaf.
– origin C15: from Anglo-Norman Fr., from OFr. quatre ‘four’ + foil ‘leaf’.
'quatrefoil' also found in these Oxford entries:

