misadd

From mis- +‎ add.

misadd (third-person singular simple present misadds, present participle misadding, simple past and past participle misadded)

1. To add incorrectly.

   Coordinate terms: miscount, mistotal

   • 1837, Joseph Chitty, The Practice of the Law in All Its Principal Departments, page 116:

     And where a barrister, in summing up the items proved before him as arbitrator, misadded them, and thereby by mistake omitted 23l. in favour of the plaintiff, the Court, even at the instance of the barrister, would not allow an amendment, the defendant's counsel objecting.