1. Likely to spread and cause an epidemic disease
   "plaguey fevers";
   - pestilent, pestilential, pestiferous
    
2. Causing irritation or annoyance
   "a plaguey newfangled safety catch";
   - annoying, bothersome, galling, irritating, nettlesome, pesky [informal], pestering, pestiferous, plaguy, teasing, vexatious, vexing, irksome, niggly, dratted [informal], aggravating

1. In a pernicious or annoying manner
   "it's so plaguey cold!";
   - plaguy, plaguily [archaic]

See also: disagreeable, epidemic