ebb (n.) Look up ebb at Dictionary.com
Old English ebba "ebb, low tide," perhaps from Proto-Germanic *abjon (cognates: Old Frisian ebba, Old Saxon ebbiunga, Middle Dutch ebbe, Dutch eb, German Ebbe), from *ab-, from PIE root *apo- "off, away" (see apo-). Figurative sense of "decline, decay" is c.1400.
ebb (v.) Look up ebb at Dictionary.com
Old English ebbian, from the root of ebb (n.). Related: Ebbed; ebbing.