i came across this word and tried to think of a translation, but I'm not entirely sure. The following things I know:
It comes from the word θνησκω wich means 'to die' and when it's in perfectum form you translate it as
'to be dead' or 'to be killed'
I can see that it's a perfectum participle, and that its middle and accusative singular, but with the sudden ξ in de middle I got a ...