Auto merge of #27922 - tshepang:dst-definition, r=alexcrichton

I am not sure this would work... I didn't test.

Author: bors

src/doc/trpl/glossary.md

@@ -38,6 +38,12 @@ let z = (8, 2, 6);
 
 In the example above `x` and `y` have arity 2. `z` has arity 3.
 
+### DST (Dynamically Sized Type)
+
+A type without a statically known size or alignment. ([more info][link])
+
+[link]: ../nomicon/exotic-sizes.html#dynamically-sized-types-(dsts)
+
 ### Expression
 
 In computer programming, an expression is a combination of values, constants,