to dip: to put something into a liquid, whether to wet just its surface or to plunge it fully under
At its core this word names one plain physical action: bringing an object into a liquid so the liquid clings to it or covers it. The liquid is almost always something specific in the scene, blood, water, oil, honey, or the sour wine at a meal, and the object can be as small as a fingertip or as large as a whole person.
The same action shows up in two everyday settings without changing meaning. In ordinary life someone dips a piece of bread in the vinegar at mealtime, dips the tip of a staff in a honeycomb, dips a foot in oil, or dips a garment in blood to fake a death. In worship a priest dips a finger in sacrificial blood, or dips hyssop and other items in blood and water, as part of making a person or place clean. The word describes the motion of dipping, not the purpose behind it.
How much of the object goes under depends entirely on the scene. Often it is a light touch: a finger, a morsel, the edge of the priests' feet at the river's brim. But it can be a full plunge, as when Naaman dips himself seven times in the Jordan to be healed, or when Job cries that God would plunge him into a pit of filth. Because of that fuller use, the Greek Old Testament translated this verb with the word that later became the standard term for immersion, which is why this simple Hebrew verb sits in the background of much later discussion about baptism. A close cousin in sense is רָחַץ, to wash or bathe: in the Naaman story the prophet tells him to wash, and Naaman does it by dipping.