decennial

adjective

1. of or for ten years.
2. occurring every ten years.

noun

3. a decennial anniversary.
4. its celebration.

adjective

1. lasting for ten years
2. occurring every ten years

noun

3. a tenth anniversary or its celebration

adj.

1680s, from Latin decennium, from decennis “of 10 years,” from decem “ten” (see ten) + annus “year” (see annual). For vowel change, see biennial.