"The Prostitute who sits on many waters"

This is the symbology of the book of Revelation, a harlot who sits on many waters.
'Sitting can have many different meanings, but in the link below, a similar type of sitting is described.

See example at: http://www.businessinsider.com/stocks-gop-congress-sitting-democrat-president-2014-11

The terms used are 'sitting President" and mean one who is 'in office' and 'on the job', 'engaging in the tasks of their position.'

κάθημαι kathēmai- is the root , translated here and elsewhere as 'place', and 'dwell', so with these meanings we can put together - "the sitting Harlot (is in office) in her place where she dwells and engages in activity from."