A thoughtcrime is an occurrence or instance of controversial or socially unacceptable thoughts. The term is also used to describe some theological concepts such as disbelief or idolatry,  or a rejection of strong philosophical or social principles. 
The term was popularized in the dystopian novel Nineteen Eighty-Four by George Orwell, wherein thoughtcrime is the criminal act of holding unspoken beliefs or doubts that oppose or question the ruling party. In the book, the government attempts to control not only the speech and actions, but also the thoughts of its subjects. To entertain unacceptable thoughts is known as crimethink in Newspeak, the ideologically purified dialect of the party.  "Crimestop" is a way to avoid crimethink by immediately purging dangerous thoughts from the mind.
Some modern publishers have described people who were being prosecuted and burned at the stake for heresy in various Abrahamic religions, as being victims of thoughtcrime laws. Such victims of thoughtcrime laws would sometimes be offered the chance to repent for their thoughtcrimes. 
People were similarly executed, or imprisoned in concentration camps, for thoughtcrime during the 20th century in totalitarian regimes, such as Stalinist USSR, Maoist China, and Cambodia under the Khmer Rouge.
The word is also used in instances where people are prevented from voicing opinions which are politically incorrect or which others may potentially be offended by. This prevention may affect speech, writing, and other forms of expression. The punishment of apostasy in sharia law is sometimes interpreted as being the death penalty, which has been described as a thoughtcrime. 
BoyLover "thought crimes"
BoyLovers are being prosecuted for "thought crimes". A common argument for harsh punishment of child pornography offenders is that their thought patterns may put them at higher risk of having sex with children.
Psychological evaluations are already being used as evidence for determining what sentences should be imposed on boylovers in the criminal justice system, and whether people who have not been convicted of any crime against minors should be allowed to raise their own children (see Santosky v. Kramer, allowing parental rights to be terminated if certain findings are made based on clear and convincing evidence). Advances in brain imaging and neuroscience may make it easier to identify a person's "dangerous" thoughtcrimes for forensic purposes.
The Diagnostic and Statistical Manual of Mental Disorders is essentially a statute book of forbidden thought patterns, promulgated by the quasi-legislative American Psychiatric Association. Having a mental disorder that poses a danger to oneself or others allows courts to take away the person's liberty without his having been found guilty beyond a reasonable doubt of having committed a crime, per Addington v. Texas.
- Papers in Ethics and Social Philosophy: - Volume 3 - Page 107, David Lewis - 2000
- Evidence, Policy and Practice: Critical Perspectives in Health and Social Care, Jon Glasby - 2011, p 22
- Orwell, George; Rovere, Richard Halworth (1984) , The Orwell Reader: Fiction, Essays, and Reportage, San Diego: Harcourt, Brace, p. 409, ISBN 0-15-670176-6.
- Renaissance Self-Fashioning: From More to Shakespeare, Stephen Greenblatt - 2012
- Critique: Review of the Department of State's Country Reports on Human Rights Practices- Page 330, Lawyers Committee for Human Rights, 1992
- Thoughtcrime (dictionary)
- When "making friends" becomes a "crime"!
- Child pornography
- Read online/download "The Perverse Law of Child Pornography by Amy Adler at this link: