vitthāra : [m.] explanation; detail; the breadth.

A.P. Buddhadatta Mahathera, Concise Pali-English and English-Pali Dictionary [available as digital version from Metta Net, Sri Lanka]

vitthāra [fr, vi+stṛ] 1. expansion, breadth; instr. vitthā- rena in breadth Miln 17; same abl. vitthārato J i.49. -- 2. extension, detail; often in C. style, introducing & detailed explanation of the subject in question, either with simple statement "vitthāro" (i. e. here the foll. detail; opp. sankhepa), e. g. DA i.65, 229; SnA 325 [cp. same in BSk. "vistaraḥ," e. g. Divy 428], or with cpds. ˚kathā SnA 464; PvA 19; ˚desanā SnA 163; ˚vacana SnA 416. Thus in general often in instr. or abl. as adv. "in detail," in extenso (opp. sankhittena in short): vitthārena D iii.241; S iv.93; A ii.77, 177, 189; iii.177; Pug 41; PvA 53, 113;vitthārato Vism 351, 479; PvA 71, 77, 81. Cp. similarly BSk. vistarena kāryaŋ Divy 377.

Pali-English Dictionary, TW Rhys Davids, William Stede,