'post-mitotic' originates from Latin and Modern scientific formation: the prefix 'post-' (Latin 'post') meaning 'after', combined with 'mitotic' derived from 'mitosis' (from Greek 'mitos' via New Latin), where 'post-' meant 'after' and 'mitos' meant 'thread'.

'Mitosis' was coined in Modern/Neo-Latin (from Greek 'mitos' meaning 'thread') in the late 19th century to describe the thread-like appearance of chromosomes during cell division; the adjective 'mitotic' derived from that noun, and later the compound 'post-mitotic' was formed by adding the Latin prefix 'post-' to indicate the period or state after mitosis.

Initially it literally indicated 'after mitosis' (the time following cell division); over time it became used more specifically to describe cells that have permanently or effectively ceased dividing (i.e., non-dividing or terminally differentiated cells).