Decennially

Part of speech: adverb

Definitions

1. Occurring or happening every ten years; taking place once a decade; recurring at ten-year intervals
2. Describing events or actions that happen once in a ten-year span; happening every tenth year without fail; marking a period of ten years between occurrences
3. Indicating a cycle or occurrence happening once per ten-year period; denoting repetition at decadal intervals; relating to something that recurs once per decade

Etymology: "Decennially" is an adverb built in the most straightforward way: the adjective "decennial" with the adverbial suffix "-ly" attached. "Decennial" itself comes from Latin "decennium," a period of ten years, combining "decem" (ten) with "annus" (year). The "-al" ending turns the noun-like idea of a decade into an adjective meaning "occurring every ten years" or "lasting ten years," and adding "-ly" converts that adjective into an adverb describing how something happens: once every ten-year span, without fail. The pattern is a familiar one in English. Many adjectives ending in "-al" take "-ly" to become adverbs, so "decennially" follows the same route as words like "annually" or "biennially," which share the same Latin-derived structure with different numerical prefixes. The adverb's meaning stays close to its base, so there is little semantic drift to trace.

Synonyms: every ten years, once a decade