to wash with water: to rinse the body or a part of it clean
One plain action runs through every use of this word: applying water to a body to make it clean. What changes is the scope and the setting, not the core act. Sometimes it is the whole body, a full bath after travel, after mourning, or to prepare oneself to be seen. Sometimes it is only a part, the dusty feet of a guest or the hands before a meal, the small courtesies of ordinary life.
The same washing carries enormous weight in worship. Israel's law made bathing with water the standard way a person who had become unclean returned to the community, and it required the priests to wash their hands and feet before serving and to rinse parts of the animals offered in sacrifice. Here the water is doing more than removing dirt: it marks the line between common and holy, between defiled and fit to approach God.
Because washing so cleanly pictures becoming clean, the word also turns figurative. To wash one's hands is to declare oneself innocent of a deed; to wash one's steps in butter is to live in such plenty that even your feet swim in richness; to wash your feet in the blood of the wicked is the language of total victory. In each case no literal bath is in view, but the image of water making something clean (or of liquid in lavish supply) is doing the work.
This word is specifically washing the body or things with water. A closely related word covers the laundering of cloth and garments, and Hebrew keeps the two jobs apart, so the choice of word itself tells you whether a person or a fabric is being cleaned.