diff --git a/hist-pl.cabal b/hist-pl.cabal
--- a/hist-pl.cabal
+++ b/hist-pl.cabal
@@ -1,5 +1,5 @@
 name:               hist-pl
-version:            0.2.0
+version:            0.2.1
 synopsis:           Umbrella package for the historical dictionary of Polish
 description:
     The package provides a tool for creating and searching the
diff --git a/src/NLP/HistPL/Analyse.hs b/src/NLP/HistPL/Analyse.hs
--- a/src/NLP/HistPL/Analyse.hs
+++ b/src/NLP/HistPL/Analyse.hs
@@ -133,14 +133,18 @@
 -- | JSON serialization configuration.  Depending on the configuration,
 -- different parts of the result will be converted to a JSON format.
 data JConf = JConf
-    { showCont :: ShowCont }
-    deriving (Show, Eq, Ord)
+    { showCont  :: ShowCont
+    -- ^ When to show cont. interpretations.
+    , showDefs  :: Bool
+    -- ^ Show definitions?
+    } deriving (Show, Eq, Ord)
 
 
 -- | Default JSON serialization configuration.
 defaultJConf :: JConf
 defaultJConf = JConf
-    { showCont = ShowCont }
+    { showCont  = ShowCont
+    , showDefs  = False }
 
 
 -- | Build JSON value from a list of analysed sentences.
@@ -175,16 +179,19 @@
 
 -- | JSON represesentation of a historical interpretation.
 jsonHist :: JConf -> (H.LexEntry, H.Code) -> Value
-jsonHist jc (entry, code) = object
-    [ "id"    .= jsonID (H.lexId entry, code)
-    , "pos"   .= map toJSON (H.pos entry)
-    , "base"  .= map toJSON (H.text $ H.lemma entry) ]
+jsonHist jc (entry, code) = object $
+    [ "id"   .= jsonID (H.lexId entry, code)
+    , "pos"  .= H.pos entry
+    , "base" .= H.text (H.lemma entry) ]
+    ++ if showDefs jc then [defsElem] else []
   where
     jsonID (id', cd') = toJSON (toJSON id', jsonCode cd')
     jsonCode code' = toJSON $ case code' of
         H.Orig -> "orig" :: T.Text
         H.Both -> "both"
         H.Copy -> "copy"
+    defsElem = "defs" .= concatMap H.text (getDefs entry)
+    getDefs  = concatMap H.defs . H.senses
 
 
 -- | JSON represesentation of a contemporary interpretation.
diff --git a/tools/hist-pl.hs b/tools/hist-pl.hs
--- a/tools/hist-pl.hs
+++ b/tools/hist-pl.hs
@@ -51,7 +51,8 @@
     , transFlag     :: Bool
     , rmHypFlag     :: Bool
     , compact       :: Bool
-    , printCont     :: Int }
+    , printCont     :: Int
+    , printDefs     :: Bool }
   deriving (Data, Typeable, Show)
 
 
@@ -79,7 +80,8 @@
     , compact = False &= help "Compact JSON output"
     , printCont = 1 &= (help . unwords)
         [ "Printing contemporary interpretations:"
-        , "0 -- never, 1 -- when no hist (default), 2 -- always" ] }
+        , "0 -- never, 1 -- when no hist (default), 2 -- always" ]
+    , printDefs = False &= help "Print definitions" }
 
 
 argModes :: Mode (CmdArgs HistPL)
@@ -130,7 +132,7 @@
     rmHyp | rmHypFlag = A.rmHyphen
           | otherwise = id
     onLine hpl
-        = fmap (encode . A.jsonAna A.defaultJConf)
+        = fmap (encode . A.jsonAna jsonConf)
         . A.mapL (A.anaWord hpl . trans)
         . A.tokenize . L.toStrict
     trans   | transFlag = T.pack . I.transliter I.impactRules . T.unpack
@@ -141,4 +143,5 @@
         { A.showCont = case printCont of
             0   -> A.NoShowCont
             2   -> A.ForceShowCont
-            _   -> A.ShowCont }
+            _   -> A.ShowCont
+        , A.showDefs = printDefs }