Is there a specific word such as racism or sexism that describes discrimination based solely on handedness?
Wiktionary and Collins English Dictionary define the term handism.
(rare) prejudice or bias based on whether a person is left-handed or right-handed
• 1993, Stanley Coren, The left-hander syndrome
Here again the right hand is salvation and the left hand damnation. Contemporary Islamic countries are an interesting example of how handism, as expressed in religious traditions, can also influence more secular activities.
discriminination against people on the grounds of whether they are left-handed or right-handed
As noted, this term is extremely rare.
"Bias" is used to describe the favoritism shown to right-handers as this article headline shows:
"Bias" as defined by the Google Dictionary:
noun: bias; plural noun: biases
- prejudice in favor of or against one thing, person, or group compared with another, usually in a way considered to be unfair.
Examples.: "there was evidence of bias against foreign applicants", "he accused the media of bias"
verb: bias; 3rd person present: biases; past tense: biased; past participle: biased; gerund or present participle: biasing
- cause to feel or show inclination or prejudice for or against someone or something.
Example: "readers said the paper was biased toward the conservatives"
Bias against left-handed people seems to be the common definition which, according to the following source, has generated many prejudices trough the centuries.
It is discrimination, conscious or not, against people who are left-hand dominant. Approximately 8–15% of the world's population is left-handed.1 Yet many common tools are designed solely for use by right-handed people, making them difficult, painful, or unsafe for left-handed people to use. These range from simple objects such as scissors to dangerous machinery such as power saws.
Beyond such neglect, however, left-handed people have frequently been subjected to deliberate discrimination and disparagement. In many societies, they are considered unlucky or even malicious by the right-handed majority. Many languages use references to left-handedness to convey awkwardness, dishonesty, stupidity, or other undesirable qualities. Even in relatively "modern" societies, left-handed people historically have been—and in some places still are—forced from childhood to use their right hands for tasks which they would naturally perform with the left, such as eating and writing.
I'm going to coin a term here and use handednessism. Never be afraid to coin a word, english has a long tradition of phrase coinage.