Definition of "fourfold"

fourfold

adjective
not comparable
1. Four times as great; quadruple.
2. Comprised of four individual members.
  Quotations
  Most pupils have a fourfold object in studying a language; they wish to be able to read and write, to speak and to understand it.
  1895, [Charles Hardy], The Aural System […]‎, page 5
adverb
not comparable
1. By a factor of four.
  Quotations
  And he shall restore the Lambe fourefold, because he did this thing, and because he had no pittie.
  1611, The Holy Bible, […] (King James Version), London: […] Robert Barker, […], 2 Samuel 12:6
verb
third-person singular simple present fourfolds, present participle fourfolding, simple past and past participle fourfolded
1. To increase to four times as much; to multiply by four.
noun
plural fourfolds
1. (mathematics) An algebraic variety of degree 4.
  Quotations
  Our main application is to the classification of Poisson brackets on Fano fourfolds.
  2015, Brent Pym, “Elliptic singularities on log symplectic manifolds and Feigin--Odesskii Poisson brackets”, in arXiv‎