In a legal context, a chilling effect is the inhibition or discouragement of the legitimate exercise of natural and legal rights by the threat of legal sanction.
Natural and legal rights are two types of rights.
Baguilat: Attacks on De Lima creating 'chilling effect' by ABS-CBN News
The right that is most often described as being suppressed by a chilling effect is the US constitutional right to free speech.
Sharyl Attkisson: Obama Has 'Chilling Effect' on Journalism by Washington Free Beacon
A chilling effect may be caused by legal actions such as the passing of a law, the decision of a court, or the threat of a lawsuit; any legal action that would cause people to hesitate to exercise a legitimate right for fear of legal repercussions.
When that fear is brought about by the threat of a libel lawsuit, it is called libel chill.
Defamation—also calumny, vilification, and traducement—is the communication of a false statement that harms the reputation of an individual person, business, product, group, government, religion, or nation.
A lawsuit initiated specifically for the purpose of creating a chilling effect may be called a Strategic Lawsuit Against Public Participation, or more commonly, a "SLAPP suit".
"Chilling" in this context normally implies an undesirable slowing.
Outside of the legal context in common usage; any coercion or threat of coercion can have a chilling effect on a group of people regarding a specific behavior, and often can be statistically measured or be plainly observed.
Coercioninjury or psychological harm in order to enhance the credibility of a threat.
For example, the news headline "Flood insurance [price] spikes have chilling effect on some home sales," and the abstract title of a two‐part survey of 160 college students involved in dating relationships: "The chilling effect of aggressive potential on the expression of complaints in intimate relationships."