CSI noun6 •Initialism of crime scene investigation (a term of forensic science). •(informal) Initialism of crime scene investigator.'Damn cops,' said a CSI, who concentrated on the holes in the bark of a tree, the only holes not made by gun-happy rat killers. — 2012 •Initialism of Customer Satisfaction Index. •Initialism of channel state information. •Initialism of consumer safety inspector. •Initialism of Companion of the Order of the Star of India. formsCSIs