Basically a level just above indestructible, usually applicable to a person/
living entity. In general, dispite being indestructible, a fight between an indestructible being and an indefuckingstructible being will be won by the latter. Along with this title, there is a general implied
awesomness of some sort, meriting the distinction over the lesser counter part, "indestructible".
"
Wow, you'd think
Bra'tac would have died by the tenth season, with all he'
s been through, but no, I suppose he's just indefuckingstructible"