A Grammatical Dictionary of Botanical Latin

verso: (a participle in the ablative absolute), part of a phrase: verso folio, 'the page having been turned' generally used to refer to the left hand page of a book (Ehrlich 1985); see recto.

Verso (Eng. noun), see versus,-a,-um (part.A): verto (part.A, abl.sg.): the left or back (i.e. turned) side, part of a phrase: verso folio, on the turned (i.e. back) side of the leaf; a left-hand page of an open book, or the back of a loose document. By convention, in book-publishing, all verso pages have even numbers (recto pages are odd numbered) (Dictionary.com Oct2018). “The two opposite pages themselves are called folium rectum and folium versum in Latin” (“recto and verso” Wikipedia Oct2018); “NL verso (folio) ‘the page being [having been] turned;’ “the side of a leaf (as of a manuscript) that is to be read second – contrasted with recto [i.e. to be read first]; a left-hand page (as of a book) usu. carrying an even page number” (WIII).

NOTE: from Latin vertere to turn + folium a leaf.

NOTE: “The ablative recto, verso already imply that the text on the page (and not the physical page itself) are referred to” (“recto and verso” Wikipedia Oct2018).

NOTE: abbrev. fol.v., or f.v.