The Collaborative International Dictionary
Mainprising
Mainprise \Main"prise\, v. t. [imp. & p. p. Mainprised; p. pr. & vb. n. Mainprising.] (Law) To suffer to go at large, on his finding sureties, or mainpernors, for his appearance at a day; -- said of a prisoner.
Wiktionary
mainprising
vb. (present participle of mainprise English)