master key (noun) master key: key opening all locks of a place
Sinonime: bitter,
depressing,
disagreeable, disconcerting, discouraging, disheartening, displeasing,
distasteful,
failing, falling short, frustrating,
inadequate,
ineffective,
inferior,
insufficient,
lame,
mediocre, unfulfilling,
unhappy, uninteresting,
unpleasant, unsatisfying
Antonime: encouraging,
pleasing,
satisfactory