Definition of "forme"

And first, although there were more things in nature then words which did expresse them, yet even in these mute and silent discourses, to expresse complexed significations, they took a liberty to compound and piece together creatures of allowable formes unto mixtures inexistent […]

1650, Thomas Browne, Pseudodoxia Epidemica: […], 2nd edition, London: […] A[braham] Miller, for Edw[ard] Dod and Nath[aniel] Ekins, […]

Both these formes, with running titles intact, were retained to print sheet D of Q2.

1978, David A. Bloestein, Introduction, John Marston, David A. Bloestein (editor), Parasitaster: Or, The Fawn, page 47

Q2 was printed in twenty-two formes.

1994, Jay L. Halio, Introduction, Jay L. Halio (editor), William Shakespeare, The First Quarto of King Lear, page 21

In casting off, the printing house would judge the length of a manuscript to determine both how many sheets would be needed, and what the divisions were between one forme and another. (A forme is one side of a sheet: four quarto pages or two folio pages.) Because formes do not have many consecutive pages, estimates would be further broken down by page. If a quarto forme includes a putative page one, for instance, that side of the sheet would also include pages four, five, and eight.

2011, Eugene Giddens, How to Read a Shakespearean Play Text, page 41