flustered
Concise Oxford English Dictionary © 2008 Oxford University Press:
fluster/ˈflʌstə(r)/
▶verb (often as adj. flustered) make (someone) agitated or confused. ▶noun a flustered state.
– origin C17 (in the sense ‘make slightly drunk’): perh. of Scand. origin and rel. to Icelandic flaustra ‘hurry, bustle’.
'flustered' also found in these Oxford entries:

