1) Coastal recession 2) Cyclic recession 3) Deep recession 4) Drop in the ocean 5) Good time for a beachcomber 6) Low water 7) Low water precursor 8) Ocean movement 9) Oceanic reflux 10) Outflow 11) Period of decline 12) Prime time for clammers 13) Receding ocean movement 14) Refluent phenomenon 15) Righteous Brothers hit 
[n] - the tide while water is flowing out
noun the tide while water is flowing out