" unintentionally "

1: as in accidentally, inadvertently;

•  Synonyms : 

•  accidentally,

•  fortuitously,

•  inadvertently,

•  unconsciously,

•  unwittingly,

•  arbitrarily,

•  capriciously,

•  carelessly,

•  casually,

•  indiscriminately,

•  informally,

•  offhand,

•  offhandedly,

•  promiscuously,

•  whimsically,

•  disconnectedly,

•  disjointedly,

•  fitfully,

•  intermittently,

•  spottily,

•  unpredictably,

•  aimlessly,

•  anyhow,

•  anyway,

•  anywise,

•  desultorily,

•  erratically,

•  haphazard,

•  haphazardly,

•  helter-skelter,

•  hit or miss,

•  irregularly,

•  randomly,

•  willy-nilly,

•  higgledy-piggledy,

•  topsy-turvy

•  Antonyms : 

•  methodically,

•  systematically,

•  carefully,

•  formally,

•  gingerly,

•  meticulously,

•  orderly,

•  punctiliously,

•  deliberately,

•  intentionally,

•  purposefully,

•  purposely

1: happening by chance;

  * e.g., " ... an unintentional encounter with an old classmate at the mall "

•  Synonyms : 

•  accidental,

•  casual,

•  chance,

•  fluky,

•  fortuitous,

•  inadvertent,

•  incidental,

•  unintended,

•  unplanned,

•  unpremeditated,

•  unwitting

•  Antonyms : 

•  calculated,

•  deliberate,

•  intended,

•  intentional,

•  planned,

•  premeditated,

•  premeditative,

•  prepense,

•  set

2: not made or done willingly or by choice;

  * e.g., " ... an unintentional insult that nevertheless was very hurtful "

•  Synonyms : 

•  coerced,

•  forced,

•  involuntary,

•  unintended,

•  unwilling,

•  will-less

•  Antonyms : 

•  deliberate,

•  freewill,

•  intentional,

•  uncoerced,

•  unforced,

•  voluntary,

•  willful,

•  willing