annual (adj.) Look up annual at Dictionary.com
late 14c., from Old French annuel (12c.) or directly from Late Latin annualem (nominative annualis), corresponding to Latin annalis as adjective form of annus "year," from PIE *at-no-, from root *at- "to go," on notion of "period gone through" (cognates: Sanskrit atati "goes, wanders," Gothic aþnam (dative plural) "year," Oscan akno- "year, holiday, time of offering"). Used of plants since 1710.
annual (n.) Look up annual at Dictionary.com
c.1400, originally "service commemorating the anniversary of a person's death," from annual (adj.). By 1824 as short for annual plant.