This is how Chicago mobsters describe business activities that are not illegal. Gangsters often invest ill-gotten monies into legitimate businesses, which, in turn, generate what they consider to be legitimate profit. Such business are referred to being "on the legit" (despite being an essential part of a larger money-laundering enterprise).

When something is legit and you need to add the ness

the measure or relative amount of something's legitness.

A word hipsters are trying to use to replace "cool" and "awesome." As if hipsters needed help, they sound less intelligent every time they use the word incorrectly in this way.

The degree of how legitimate something is.

A word that has become way overused by this generation.

for real, truthful