Hoplophobia is a political neologism coined by retired American military officer Jeff Cooper as a pejorative to describe an "irrational aversion to weapons." It is also used to describe the "fear of firearms" or the "fear of armed citizens." Hoplophobia is a political term and not a recognized medical phobia.

Most phobias are classified into three categories and, according to the "Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition" (DSM-V), such phobias are considered to be sub-types of anxiety disorder. The categories are:

1. Specific phobias: Fear of particular objects or social situations that immediately results in anxiety and can sometimes lead to panic attacks. Specific phobia may be further subdivided into five categories: animal type, natural environment type, situational type, blood-injection-injury type, and other.

2. Agoraphobia: a generalized fear of leaving home or a small familiar 'safe' area, and of possible panic attacks that might follow. It may also be caused by various specific phobias such as fear of open spaces, social embarrassment (social agoraphobia), fear of contamination (fear of germs, possibly complicated by obsessive-compulsive disorder) or PTSD (post traumatic stress disorder) related to a trauma that occurred out of doors.

3. Social phobia, also known as social anxiety disorder, is when the situation is feared as the person is worried about others judging them.

Phobias vary in severity among individuals. Some individuals can simply avoid the subject of their fear and suffer relatively mild anxiety over that fear. Others suffer full-fledged panic attacks with all the associated disabling symptoms. Most individuals understand that they are suffering from an irrational fear, but are powerless to override their panic reaction. These individuals often report dizziness, loss of bladder or bowel control, tachypnea, feelings of pain, and shortness of breath.

Unlike specific phobias, social phobias include fear of public situations and scrutiny, which leads to embarrassment or humiliation in the diagnostic criteria.

American firearms expert and retired Marine colonel Jeff Cooper coined the word in 1962 to denigrate and anger proponents of gun control by implying that their thoughts were "aberrant" and unreasoning:

I coined the term "hoplophobia" in 1962 in response to a perceived need for a word to describe a mental aberration consisting of an unreasoning terror of gadgetry, specifically, weapons. The most common manifestation of hoplophobia is the idea that instruments possess a will of their own, apart from that of their user. This is not a reasoned position, but when you point this out to a hoplophobe he is not impressed because his is an unreasonable position. To convince a man that he is not making sense is not to change his viewpoint but rather to make an enemy. Thus hoplophobia is a useful word, but as with all words, it should be used correctly.

The term was constructed from the Greek ὅπλον – "hoplon", meaning, amongst other things, "arms," and φόβος – "phobos", meaning "fear." Cooper employed the term as just another alternative to other slang terms, stating: "We read of 'gun grabbers' and 'anti-gun nuts' but these slang terms do not [explain this behavior]." Cooper's conjecture was that "the most common manifestation of hoplophobia is the idea that instruments possess a will of their own, apart from that of their user." Writing in an opinion piece, "Pittsburgh Tribune-Review" columnist Dimitri Vassilaros said that the term was intended by Cooper as tongue-in-cheek to mock those who think guns have free will.