Etymology tree English ecology Proto-Indo-European *-ikos Proto-Italic *-ikos Latin -icuslbor. Old French -iquebor. Middle English -ic Proto-Indo-European *h₂el-der.? Proto-Italic *-ālis Latin -ālisbor. Old French -albor. ▲ Latin -ālis Old French -elbor. ▲ Latin -ālisbor. Middle English -al Middle English -ical English -ical English ecological From ecology + -ical.