[MRG] Fix small spelling mistake in comment
diff --git a/sklearn/utils/metaestimators.py b/sklearn/utils/metaestimators.py
index ff16cd3671955..ae909140b10e0 100644
--- a/sklearn/utils/metaestimators.py
+++ b/sklearn/utils/metaestimators.py
@@ -45,7 +45,7 @@ def _set_params(self, attr, **params):
         for name in list(six.iterkeys(params)):
             if '__' not in name and name in names:
                 self._replace_estimator(attr, name, params.pop(name))
-        # 3. Step parameters and other initilisation arguments
+        # 3. Step parameters and other initialisation arguments
         super(_BaseComposition, self).set_params(**params)
         return self
 

#### Reference Issues/PRs
fixes a typo introduced in #1769

#### What does this implement/fix? Explain your changes.
just fixes a small spelling mistake in a comment