To hit something gently, and often repeatedly, especially making short, sharp noises. (Cambridge Dictionary)
To touch the screen of a phone, tablet computer, etc. in order to give an instruction for something to happen. (Cambridge Dictionary). (Cambridge Dictionary)
To strike lightly especially with a slight sound. (Merriam – Webster)
To give a light blow with. (Merriam – Webster)
To bring about by repeated light blows. (Merriam – Webster)
To repair by putting a tap on. (Merriam – Webster)
If you tap something, you hit it with a quick light blow or a series of quick light blows. (Collins Dictionary)
A device by which a flow of liquid or gas from a pipe or container can be controlled. (Oxford Dictionaries)
Tap and sink images.
A tap on the shoulder.