diff --git a/src/english/ParadigmsEng.gf b/src/english/ParadigmsEng.gf
index 1a56707b4..3aa7303cb 100644
--- a/src/english/ParadigmsEng.gf
+++ b/src/english/ParadigmsEng.gf
@@ -168,6 +168,7 @@ oper
     compoundA : A -> A ; -- force comparison with more/most
     simpleA   : A -> A ; -- force comparison with -er,-est
     irregAdv  : A -> Str -> A ;  -- adverb irreg, e.g. "fast"
+    invarA    : Str -> A ; -- adjective that does not vary in morphology
 
 --3 Two-place adjectives
 
@@ -654,6 +655,8 @@ mkInterj : Str -> Interj
       mkAdjective a b c d
     } ;
 
+  invarA s = mkAdjective s s s s ;
+
   compoundA = compoundADeg ;
   simpleA a = 
     let ad = (a.s ! AAdj Posit Nom)