burn ‧ out /ˈbɜːnaʊt $ ˈbɜːrn-/ BrE AmE noun
1 . [uncountable] the feeling of always being tired because you have been working too hard:
Many of the teachers are suffering from burnout.
2 . [uncountable and countable] the time when a ↑ rocket or ↑ jet has finished all of its ↑ fuel and stops operating