Annual
late Middle English: from Old French annuel, from late Latin annualis, based on Latin annus ‘year’.
wiktionary
First attested around 1382, borrowed from Late Latin annuālem, annuālis, related to Latin annālis, adjective form of annus(“year”). Used to categorize plants since 1710.
etymonline
annual (adj.)
late 14c., "appointed by the year;" c. 1400, ""occurring or done once a year," from Old French annuel "yearly" (12c.) or directly from Medieval Latin annualis "yearly," corresponding to Latin annalis as adjective form of annus "year."
This is reconstructed to be from Proto-Italic *atno- "year" (compare Oscan akno- "year, holiday, time of offering"), from PIE *at-no- "which goes," also "a year" (as "going around"), suffixed form of root *at- "to go" (source also of Sanskrit atati "goes, wanders," atamana- "to travel, wander," atya- "steed, runner"). The root also has Germanic derivatives meaning "a year," such as Gothic aþnam (dative plural) "year."
annual (n.)
c. 1400, originally "service commemorating the anniversary of a person's death," from annual (adj.) or from Late Latin annualem (nominative annualis). By 1680s as "plant that grows again or blooms every year," also as "annual literary publication."
