'posterosuperior' originates from Neo-Latin/compound formation, specifically combining Latin 'poster-' (from 'posterus') meaning 'coming after, behind' and Latin 'superior' (from 'superus') meaning 'above'.

'posterosuperior' was formed in modern medical/Latin usage by combining the Latin elements 'poster(o)-' and 'superior' to create a precise directional term used in anatomy and clinical descriptions.

Initially the components meant 'behind' and 'above' in Latin; over time they were combined in scientific terminology to form the specific anatomical descriptor 'posterosuperior', with its meaning remaining essentially the combined sense 'behind and above'.