accidentally in WordNet English dictionary

1. without advance planning
   "they met accidentally"
   by chance  accidentally  circumstantially  unexpectedly  by chance  accidentally  circumstantially  unexpectedly 
   
2. without intention; in an unintentional manner
   "she hit him unintentionally"
   unintentionally  accidentally  unintentionally  accidentally 
   
3. of a minor or subordinate nature
   "these magnificent achievements were only incidentally influenced by Oriental models"
   incidentally  accidentally  incidentally  accidentally