This section is from the book "Popular Law Library Vol7 Equity Jurisprudence, Trusts, Equity Pleading", by Albert H. Putney. Also available from Amazon: Popular Law-Dictionary.
"Mistake is some unintentional act, or omission, or error, arising from ignorance, surprise, imposition, or misplaced confidence."1
Another definition of mistake which has been given is as follows:
"Mistake may be said to exist, in a legal sense, where a person, acting upon some erroneous conviction, either of law or of fact, executes an instrument, or does an act, which, but for that erroneous conviction, he would not have executed or done." 2