adjective
- of or for ten years.
- occurring every ten years.
noun
- a decennial anniversary.
- its celebration.
adjective
- lasting for ten years
- occurring every ten years
noun
- a tenth anniversary or its celebration
1680s, from Latin decennium, from decennis “of 10 years,” from decem “ten” (see ten) + annus “year” (see annual). For vowel change, see biennial.