columnist n.

mid-15c., "a pillar, long, cylindrical architectural support," also "vertical division of a page," from Old French colombe (12c., Modern French colonne "column, pillar"), from Latin columna "pillar," collateral form of columen "top, summit," from PIE root *kel- (2) "to be prominent; hill."

In the military sense "formation of troops narrow in front and extending back" from 1670s, opposed to a line, which is extended in front and thin in depth. Sense of "matter written for a newspaper" (the contents of a column of type) dates from 1785.

word-forming element meaning "one who does or makes," also used to indicate adherence to a certain doctrine or custom, from French -iste and directly from Latin -ista (source also of Spanish, Portuguese, Italian -ista), from Greek agent-noun ending -istes, which is from -is-, ending of the stem of verbs in -izein, + agential suffix -tes.

Variant -ister (as in chorister, barrister) is from Old French -istre, on false analogy of ministre. Variant -ista is from Spanish, popularized in American English 1970s by names of Latin-American revolutionary movements.