ebb, ebbing, wane
Meaning: a gradual decline (in size or strength or power or number)
For a few moments more I observed the dying man, whose life was ebbing little by little.
And, it blazed upon me, I might have died there by the sheer ebbing of my will--unavenged!
On to oblivion then! On, on, and do your part, ye burying, ebbing tide! On for your time, ye furious debouche!
He rose later each day and with ebbing vigour, jotted down notes and corrections upon the proofs of the Minority Report.
Who would ever have imagined, under this terrestrial crust, an ocean with ebbing and flowing tides, with winds and storms?"
And as each body spent out of its ebbing store Of strength and hope, I felt the forward thrust, At first so sure, Fail in its rhythm, Falter slow, And slower-- Hang an endless moment-- Till in a rush came fear-- Fear of the sea, that it might win again, Gathering one crew more, Making them pay in vain.