'modern-themed' is a compound formed in English from 'modern' + 'theme' with the adjectival past-participle suffix '-ed' (forming 'themed', meaning 'having a theme'). 'modern' ultimately comes from Latin 'modernus' (from 'modo' meaning 'just now'), and 'theme' comes from Greek 'thema' via Latin/Old French meaning 'that which is set or placed'.

'modern' entered English via Middle French and Medieval Latin ('modernus') and came to mean 'belonging to the present time'; 'theme' comes from Greek 'thema' (something laid down) through Latin/French to English. The compound pattern 'X-themed' (e.g., 'child-themed', 'space-themed') developed in modern English (especially 19th–20th centuries) to form adjectives meaning 'having X as a theme', and 'modern-themed' follows this pattern.

Individually, 'modern' originally meant 'just now' and later 'of the present time'; 'theme' originally meant 'that which is laid down' and evolved to mean 'subject or motif'. Combined as 'modern-themed', the meaning is 'having a modern subject, style, or motif', a straightforward composition of the parts.