'period-appropriate' is a modern English compound combining 'period' and 'appropriate'. 'Period' ultimately comes from Greek via Latin ('periodos'/'periodus'), where 'peri-' meant 'around' and the element related to 'way' or 'coming'; 'appropriate' comes from Latin 'appropriatus' (from 'appropriare'), formed from 'ad-' (to/toward) + 'proprius' (one's own).

'period' entered English via Latin and Old French forms derived from Greek 'periodos'; 'appropriate' passed into English from Latin through Anglo-French/Old French (via 'approprier'/'appropriatus') and developed into the adjective meaning 'suitable'. The hyphenated compound 'period-appropriate' is a modern English formation (20th century usage) combining the two words to create a descriptive adjective.

Originally, elements had senses like 'period' referring to a span of time and 'appropriate' meaning 'to make one's own' or 'allocate to', but 'appropriate' evolved into an adjective meaning 'suitable'. The compound came to mean 'suitable for the given historical period'.