rem

Etymology 1

Initialism.

noun

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

Etymology 2

Abbreviation of Roentgen equivalent in man.

noun

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

Etymology 3

Shortening of remark.

noun

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

Etymology 4

Shortening of remaining.

adj

1. (knitting) Remaining.
   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

Etymology 5

Blend of root + em.

noun

1. (web design) A unit relative to the declared font size of the root element in a HTML document.
   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