Why scissors have a singular form?

Scissors have a singular form because, despite being two blades, they are considered a single tool that functions as a unit.

Here's why:

* Function: The two blades work together to perform a single action: cutting.

* Design: They are connected by a single pivot point and function as one cohesive unit.

* Usage: We refer to the tool as a whole, not as individual blades. We don't say "I used the left blade of the scissors", we say "I used the scissors".

* Historical: The word "scissors" is a plural noun but it has become a singular noun over time, similar to "pants" and "glasses".

Essentially, while scissors consist of two blades, they are perceived as a single tool with a singular function.