" harebrained "

1: lacking in seriousness or maturity;

  * e.g., " ... the movie follows the harebrained antics of a pair of stoners who seem incapable of growing up "

•  Synonyms : 

•  birdbrained,

•  ditzy,

•  dizzy,

•  featherbrained,

•  flighty,

•  frivolous,

•  frothy,

•  futile,

•  giddy,

•  goofy,

•  light-headed,

•  light-minded,

•  puerile,

•  scatterbrained,

•  scatty,

•  silly,

•  yeasty

•  Antonyms : 

•  earnest,

•  serious,

•  serious-minded,

•  sober,

•  unfrivolous

2: showing or marked by a lack of good sense or judgment;

  * e.g., " ... a harebrained idea to go for a hike in an area where grizzly bear attacks had recently been reported "

•  Synonyms : 

•  absurd,

•  asinine,

•  balmy,

•  barmy,

•  batty,

•  brainless,

•  bubbleheaded,

•  cockeyed,

•  crackbrained,

•  crackpot,

•  crazy,

•  cuckoo,

•  daffy,

•  daft,

•  dippy,

•  dotty,

•  fatuous,

•  featherheaded,

•  fool,

•  foolish,

•  fruity,

•  gaga,

•  half-baked,

•  half-witted,

•  inept,

•  insane,

•  jerky,

•  kooky,

•  loony,

•  loony tunes,

•  lunatic,

•  lunkheaded,

•  mad,

•  meshuga,

•  nonsensical,

•  nutty,

•  preposterous,

•  sappy,

•  screwball,

•  senseless,

•  silly,

•  simpleminded,

•  stupid,

•  tomfool,

•  unwise,

•  wacko,

•  wacky,

•  weak-minded,

•  witless,

•  zany

•  Antonyms : 

•  judicious,

•  prudent,

•  sagacious,

•  sage,

•  sane,

•  sapient,

•  sensible,

•  sound,

•  wise