Definition of "rem"

rem¹

noun
plural rems
1. (often capitalized) Initialism of rapid eye movement, a sleep state.

rem²

noun
plural rems
1. A dose of absorbed radiation equivalent to one roentgen of X-rays or gamma rays.

rem³

noun
plural rems
1. (computing) A remark; a programming language statement used for documentation (in BASIC for example); also used in DOS batch files.

rem⁴

adjective
not comparable
1. (knitting) Remaining.
  Quotations
  Knit 1 row. Dec 1 st at each end of next row and at each end of every foll alt row until 2 sts rem.
  2009, Sally Muir, Joanna Osborne, Diana Miller, Pet Projects: The Animal Knits Bible, page 71

rem⁵

noun
plural rems
1. (web design) A unit relative to the declared font size of the root element in a HTML document.
  Quotations
  Like the em unit, the rem unit is based on declared font size. The difference—and it’s a doozy—is that whereas em is calculated using the font size of the element to which it’s applied, rem is always calculated using the root element.
  2017, Eric A Meyer, Estelle Weyl, CSS: The Definitive Guide: Visual Presentation for the Web, Kindle edition, O'Reilly Media, page 126