lav-, lava-, lavat- +

1. A medicated liquid for external application.
2. Any of various externally applied cosmetic liquids.
3. A liquid, usually an aqueous medicinal preparation containing one or more insoluble substances and applied externally for skin disorders.
4. A liquid cosmetic preparation usually containing alcohol and a cleansing, softening, or astringent agent and applied to the skin especially of the face and hands .
5. First known recording was c.1400, from Old French lotion, from Latin lotionem (lotio), "a washing", from lotus, popular form of lautus, past participle of lavere "to wash".

The instillation and retrieval of a physiologic solution in the peritoneal cavity in order to examine the effluent for abnormal cells, bacteria, or evidence of internal bleeding following trauma.

Lavage of the pleural (rib) cavity.

Irrigation of the trachea with fluid.