preparation. lawyer Latin for "from the commencement," as "it had been legal ab initio."
Latin, for through the first work or definition from the beginning.
c.1600, Latin, literally "from the beginning," from ab "from" + oblique situation of initium "entrance, starting," pertaining to verb inire "going into, enter upon, start" (see preliminary).
in the beginning
The marriage was declared invalid ab initio either on the ground of Anne's precontract with Lord Percy or more probably on the ground of the affinity established between Henry and Anne by Henry's previous relations with Mary Boleyn.