diff --git a/pandas/core/tools/numeric.py b/pandas/core/tools/numeric.py
index 803723dab46ff..79d8ee38637f9 100644
--- a/pandas/core/tools/numeric.py
+++ b/pandas/core/tools/numeric.py
@@ -21,7 +21,7 @@ def to_numeric(arg, errors='raise', downcast=None):
 
     Parameters
     ----------
-    arg : list, tuple, 1-d array, or Series
+    arg : scalar, list, tuple, 1-d array, or Series
     errors : {'ignore', 'raise', 'coerce'}, default 'raise'
         - If 'raise', then invalid parsing will raise an exception
         - If 'coerce', then invalid parsing will be set as NaN