For the crossword clue “the R of REM,” the standard answer is RAPID.

What “the R of REM” means

  • REM in sleep science stands for Rapid Eye Movement , so the “R” in REM expands to rapid.
  • Many modern crosswords (including NYT and major syndicated puzzles) clue “the R of REM” with the 5‑letter answer RAPID.

Other possible puzzle contexts

Most of the time, if you see this clue with a 5-letter slot, the answer will be:

  • RAPID (fits the definition “R of REM” and matches common databases).

Some general crossword answer lists include alternate possibilities for different letter counts, but for the classic clue “The ‘R’ of REM” with 5 boxes, RAPID is the one you want.

Quick HTML table of key info

html

<table>
  <tr>
    <th>Clue</th>
    <th>Answer</th>
    <th>Length</th>
    <th>Notes</th>
  </tr>
  <tr>
    <td>The "R" of REM</td>
    <td>RAPID</td>
    <td>5</td>
    <td>From REM = Rapid Eye Movement; very common NYT-style answer.[web:3][web:5][web:9]</td>
  </tr>
</table>

Information gathered from public forums or data available on the internet and portrayed here.