congo red

1. 1.

   a red-brown azo dye especially as a chemical pH indicator (congo red is red in basic and blue in acidic solutions)

   Broaderazo dyeacid-base indicator

   solution

Questions about congo red

What does congo red mean?

congo red means "a red-brown azo dye especially as a chemical pH indicator (congo red is red in basic and blue in acidic solutions)".

Is congo red a common word?

congo red is banded "Uncommon" — turns up in careful writing rather than conversation. The band comes from how often the word appears in a large corpus of everyday English, not from an editor's impression.