studdingsail
Concise Oxford English Dictionary © 2008 Oxford University Press:
studdingsail /ˈstʌns(ə)l/
▶noun an additional sail on a square-rigged sailing ship, set at the end of a yard in light winds.
– origin C16: studding perh. from Mid. Low Ger., MDu. stōtinge ‘a thrusting’.
'studdingsail' also found in these Oxford entries:

