Adjective
unitless (not comparable)
(physics) Having no units of measurement; such as a ratio or percentage of two numbers which have the same units.
As such, specific gravity is a unitless value. Source: Internet
Defined as the quotient of the mass of the sample and difference between the weight of the sample in air and its corresponding weight in water, specific gravity is a unitless ratio. Source: Internet
In many cases the property of the output that varies is dependent on the same property of the input, making the gain unitless (though often expressed in decibels (dB)). Source: Internet
It is a tool for measuring the responsiveness of a variable, or of the function that determines it, to changes in causative variables in unitless ways. Source: Internet
The special function is defined in the exponential integral article, and the unitless quantity is : is a maximum or cutoff wavenumber, arising due to binary collisions, and can vary with ion species. Source: Internet