A brief, sharp, not particularly loud, relatively high-pitched sound produced by the impact of something small and hard against something hard, such as by the operation of a switch, a lock or a latch, or a finger pressed against the thumb and then released to strike the hand. quotations ▼
I turned the key, the lock gave a click and the door opened;  a click of one’s fingers
(phonetics) An ingressive sound made by coarticulating a velar or uvular closure with another closure.
tsk is a click sound in English
Sound made by a dolphin.
The act of operating a switch, etc., so that it clicks.
The act of pressing a button on a computer mouse, both as a physical act and a reaction in the software.
With the right software you can program your mouse to do a double click with a single click (but that's cheating)
(by extension) A single instance of content on the internet being accessed.