(a.) Flowing back; returning; ebbing.

antiphonal ascending axial back back-flowing backward descending down-trending downward drifting flowing fluent flying going gyrational gyratory mounting passing plunging progressive reacting reactionary reactive reflex reflexive reflowing regressive respondent responding responsive retroactionary retroactive retrogressive revulsive rising rotary rotational rotatory running rushing sideward sinking soaring streaming up-trending upward