Index: docs/Lexicon.rst
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--- docs/Lexicon.rst
+++ docs/Lexicon.rst
@@ -259,6 +259,14 @@
     In garbage collection, metadata emitted by the code generator which
     identifies `roots`_ within the stack frame of an executing function.
 
+**Splat**
+    Splat refers to a vector of identical scalar elements.
+
+    The term is based on the PowerPC Altivec instructions that provided
+    this functionality in hardware. For example, "vsplth" and the corresponding
+    software intrinsic "vec_splat()". Other hardware names for this action
+    may be "duplicate" (ARM) or "broadcast" (x86).
+
 T
 -