'period-specific' originates from modern English as a compound of 'period' and 'specific'. 'period' ultimately comes from Greek, specifically the word 'periodos', where 'peri-' meant 'around' and 'hodos' meant 'way' or 'course'; 'specific' originates from Latin, specifically the word 'specificus', from 'species' meaning 'appearance' or 'kind'.

'period' passed into English via Latin ('periodus') and Old French before becoming Middle English 'period'; 'specific' came into English from Latin 'specificus' through Medieval/Old French and Late Latin usage, eventually forming compounds like 'period-specific' in modern English to describe things tied to a time span.

Initially, components referred to a 'circuit/recurring cycle' (period) and 'of a kind/appearance' (specific); over time the compound evolved to mean 'belonging to or characteristic of a particular time or era', a sense driven by combining the temporal sense of 'period' with the limiting sense of 'specific'.