tran·quil·i·ty or tran·quil·li·ty 
(trăng-kwĭlĭ-tē, trăn-)
(trăng-kwĭlĭ-tē, trăn-)n.
The quality or state of being tranquil; serenity.
- hydromedusa
- hydromel
- hydrometallurgical
- hydrometallurgy
- hydrometeor
- hydrometeorological
- hydrometeorologist
- hydrometeorology
- hydrometer
- hydrometric
- hydrometrical
- hydrometrically
- hydrometry
- hydromorphone
- hydronaut
- hydronephrosis
- hydronic
- hydronium
- hydropath
- hydropathic
- hydropathical
- hydropathist
- hydropathy
- hydrophane
- hydrophanous