DOC mention single iteration for partial_fit in glossary
@@ -1236,7 +1236,8 @@ Methods
repeatedly calling ``partial_fit`` does not clear the model, but
updates it with respect to the data provided. The portion of data
provided to ``partial_fit`` may be called a mini-batch.
- Each mini-batch must be of consistent shape, etc.
+ Each mini-batch must be of consistent shape, etc. In iterative
+ estimators, ``partial_fit`` often only performs a single iteration.
``partial_fit`` may also be used for :term:`out-of-core` learning,
although usually limited to the case where learning can be performed
