'anti-leftist' originates from modern English, specifically the combination of the prefix 'anti-' and the noun 'leftist', where 'anti-' meant 'against' and 'leftist' denoted a supporter of the political left.

'leftist' comes from 'left' in the political sense, a usage that became prominent after the French Revolution (from French 'gauche' for the left side) and later formed the agent noun 'leftist' with the suffix '-ist'; the compound 'anti-leftist' was later formed in English by adding the prefix 'anti-' to indicate opposition.

Initially it simply meant 'against people of the political left'; over time it has retained that core meaning but has sometimes broadened to cover cultural or social opposition to left-leaning ideas as well.