It means you did it without meaning to. Merriam-Webster online defines "inadvertent" as "not intended or planned". You might do something on purpose that had an unintended effect: for example, if I drop a bag of garbage off my porch into the can below, but just as I drop it someone standing under the porch looks down into the can and the bag hits them. (I've done the first one hundreds of times; the second has never happened, and I hope it never does.) So I dropped the bag ON PURPOSE, but it hit them BY ACCIDENT, and I hit them with the bag INADVERTENTLY.
The word "accidentally" is already an adverb. It means by accident, or inadvertently.
unintentionally, incidentally, by accident, by chance, inadvertently, unwittingly, randomly, haphazardly
The word "accidentally" is a better than "on accident." I don't believe that on accident is grammatically correct. I am not sure what you mean by when to use it.
A manipulated variable is not changed on purpose.
The word is spelled "accidentally" (not on purpose, inadvertently).
By accident (As 'by' is being used as a stand in for 'as a result of an', which is similar to, 'as a result of an action of Jeff', or 'by Jeff') This also raises the question "why is it 'by accident' but 'on purpose'?" 'On purpose' implies a following of a purpose, (i.e. "on point").
on accident
accident
It was clear from the evidence that the damage caused by the fire truck was caused inadvertently, since running over the children's toys was not done on purpose.
purpose of accident reporting to prevent further occurrence and to learn a lesson from it.
Yes, men kill dolphins by accident or purpose Yes, people kill dolphins by accident or purposeYes, babies kill dolphins by accident or purposeYes, women kill dolphins by accident or purposeYes, people kill dolphins by accident or purpose
Yes, men kill dolphins on accident or purpose and both.