Wiktionary
n. 1 Fear or hatred of transsexuality or transgenderism, or of trans individuals. 2 (context chemistry English) The preference of pairs of high-trans effect soft ligands to avoid being mutually trans by becoming cis and having other low-trans effect hard ligands trans to themselves.
Wikipedia
Transphobia is a range of antagonistic attitudes and feelings against transgender or transsexual people, or against transsexuality. Transphobia can be emotional disgust, fear, anger or discomfort felt or expressed towards people who do not conform to society's gender expectations. It is often expressed alongside homophobic views and hence is often an aspect of homophobia. Transphobia is a type of prejudice and discrimination similar to racism and sexism, and transgender people of color are often subjected to all three forms of discrimination at once.
Other terms, such as cissexism, cisgenderism and cisnormativity, place more stress on societal norms that enforce the gender binary but are occasionally used synonymously with transphobia.
Child victims of transphobia experience harassment, school bullying, and violence in school, foster care, and social programs. Adult victims experience public ridicule, harassment including misgendering, taunts, threats of violence, robbery, and false arrest; many feel unsafe in public. A high percentage report being victims of sexual violence. Some are refused healthcare or suffer workplace discrimination, including being fired for being transgender, or feel under siege by conservative political or religious groups who oppose laws to protect them. There is even discrimination from a fragment of the gay rights movement.
Besides the increased risk of violence and other threats, the stress created by transphobia can cause negative emotional consequences which may lead to drug use, running away from home (in minors), and a higher rate of suicide.