Definition of offset blanket in US English:

offset blanket

noun

Printing
  • 1A protective blanket or sheet which receives excess ink and thus prevents wet images passing from one newly-printed sheet to another; a set-off sheet.

  • 2A rubber-coated sheet attached to a cylinder on an offset printing press which transfers the ink from the plate to the paper.

Origin

Early 20th century; earliest use found in The New English Dictionary.