Etymograph

English

horizontalism

From horizontal + -ism.

Formed from horizontal + -ism

Ancient Greek ὁρίζων ‘horizon’

Latin horizōn

Middle French horizontal

English horizontal

The story

The sense “equitable distribution of power” is a calque of Spanish horizontalidad, originating from the 2001 protests in Argentina.

Today it means

noun A political or social theory or system that advocates the equitable distribution of power in a society.

Language periods are conventional ranges, not dates for this word.

Etymograph / horizontalism