I. | ̷ ̷ ̷ ̷|fōld adverb
Etymology: Middle English, from thousand (I) + -fold
: by 1000 times — usually preceded by a or a numeral
increased a thousandfold
the small sum spent upon his scientific genius would be returned to the nation ten thousandfold — World's Work
II. adjective
Etymology: Middle English, from Old English thūsendfeald, from thūsend thousand + -feald -fold
: being 1000 times as large, as great, or as many as some understood size, degree, or amount : very great — usually preceded by a or a numeral (as one, four )
and with a thousandfold reverberation — S.T.Coleridge
a thousandfold increase
• thou·sand·fold·ly adverb