'polymorphonuclear-dominant' originates from Modern English as a compound of 'polymorphonuclear' and 'dominant'. 'polymorphonuclear' itself derives from Greek/Neo-Latin elements: 'poly-' meaning 'many', 'morpho-' meaning 'form', and 'nuclear' from Latin/Greek 'nucleus' meaning 'kernel' or 'core'. 'dominant' originates from Latin 'dominant-' (present participle of 'dominare'), meaning 'ruling' or 'having authority'.

'polymorphonuclear' evolved in medical Neo-Latin in the 19th century from Greek roots ('poly-' + 'morpho-') combined with Latinized 'nuclearis' to describe cells with variably shaped nuclei (e.g., polymorphonucleate). 'dominant' passed from Latin 'dominans' through Old French into Middle English as 'dominant'. The full compound was formed in modern medical English by combining the established technical adjective with 'dominant' to indicate predominance.

Individually, 'polymorphonuclear' originally described cells with multiple or variably shaped nuclei and 'dominant' meant 'ruling' or 'prevailing'. In medical contexts the compound's meaning specialized to 'characterized by a predominance of polymorphonuclear leukocytes (typically neutrophils)'.