'PMN-dominant' originates from an English medical abbreviation and a Latin-derived adjective: 'PMN' is an abbreviation of 'polymorphonuclear' (from Greek elements 'poly-' meaning 'many' and 'morphē' meaning 'form', combined with Latin 'nucleus' meaning 'kernel'), and 'dominant' originates from Latin 'dominans' (from 'dominus' meaning 'lord').

'polymorphonuclear' was formed in medical Latin/English in the 19th–20th centuries to describe multi-lobed nuclei in certain white blood cells; it was later abbreviated as 'PMN' in 20th-century clinical and laboratory usage. 'Dominant' entered English via Old French/Latin; the compound adjectival form 'PMN-dominant' arose in modern medical writing by hyphenating the abbreviation with the adjective to indicate predominance.

Initially, 'polymorphonuclear' described nuclear shape and cell type; when abbreviated to 'PMN' and combined with 'dominant' the phrase evolved to denote numerical predominance of those cells in a sample (i.e., composition rather than morphology).