litmus

«litmus» in Mova's school dictionary: a dye made from lichens that turns red in acid and blue… — its meaning for a pupil, its sense in the lessons and examples, with 2 sentences of Mova's corpora that use it.

part of speech

noun (litmus, uncountable); adjective (litmus — in litmus test, litmus paper)

meaning for a pupil

1) (science) Litmus is a dye made from lichens that turns red in acid and blue in alkali, used to test liquids. tree →

2) A litmus test is a test with litmus paper; (figurative) it is also a simple test that clearly shows what someone thinks or what something is really like. tree →

sense in the lessons

In science lessons pupils dip litmus paper into lemon juice (turns red, acid), soap water (turns blue, alkali) and pure water (no change, neutral). In everyday and political talk, «a litmus test» means one key question that shows the truth. Phrases: «litmus paper», «red litmus», «blue litmus», «litmus test».

examples

• Lemon juice turned the blue litmus paper red. tree →
• Soap turned the red litmus paper blue. tree →
• Use litmus to find out if the liquid is an acid. tree →
• Water does not change the colour of litmus. tree →
• The vote was a litmus test for the new leader. tree →
• How people treat waiters is a litmus test of their kindness. tree →

note

Uncountable: «some litmus», «litmus paper». Rule to remember: acids turn blue litmus red; alkalis turn red litmus blue. Litmus shows acid or alkali but not how strong; universal indicator gives a range of colours (pH 1–14).

In the corpora

• Scientists use indicators too: litmus paper, made from lichens, turns red in acid and blue in alkali.
• Litmus paper turns red in acid and blue in alkali; its dye comes from lichens and has been used for hundreds of years.

Trees and pragmatics

Every meaning and example of «litmus» parsed by Mova, each sentence with its dependency tree and frames.