diff --git a/doc/1-intro/glossary.md b/doc/1-intro/glossary.md
index fe8eacf8d..75b860bc3 100644
--- a/doc/1-intro/glossary.md
+++ b/doc/1-intro/glossary.md
@@ -4,7 +4,7 @@
 
 **ADPCM**: adaptive differential pulse code modulation. this is a variety of DPCM with a more complex method of storing the amplitude differences.
 
-**ADSR**: attack, decay, sustain, release. these are the four necessary values for a basic volume envelope.
+**ADSR**: attack, decay, sustain and release. these are elements that comprise a basic envelope.
 
 **algorithm**: the way in which the operators in an FM instrument interact.
 - when two operators connect to the same point, their sounds are added together.