Dehydration rhymes with:
rehydration, hydration, rehydration, hydration, rehydration, hydration, rehydration, administration, arbitration, calibration, castration, celebration, concentration, conflagration, consecration, demonstration, desecration, disintegration, duration, emigration, filtration, frustration, gyration, hydration, illustration, immigration, infiltration, integration, libration, migration, ministration, narration, nitration, oration, orchestration, penetration, proration, prostration, registration, rehydration, sequestration, vibration
Dehydration sounds like:
darden, darton, dearden, derden, deterioration, dorton, drawdown, drayton, dryden, duration, durden, durdin