triennial (n.)
- amphibian
- angiosperm
- anniversary
- annual
- bicentenary
- bicentennial
- biennial
- bimonthly
- birthday
- biweekly
- centenary
- centennial
- commemoration
- cosmopolite
- cutting
- daily
- dicot
- dicotyledon
- ephemeral
- evergreen
- fungus
- gametophyte
- gymnosperm
- hydrophyte
- jubilee
- monocot
- monthly
- perennial
- plant
- quarterly
- quincentenary
- quincentennial
- secular
- seedling
- semimonthly
- semiweekly
- sesquicentennial
- spermatophyte
- sporophyte
- tercentenary
- tercentennial
- thallophyte
- vegetable
- weed
- weekly
- yearly
triennial (adj.)
- amphibian
- annual
- biannual
- bicentenary
- bicentennial
- biennial
- bimonthly
- biweekly
- catamenial
- centenary
- centennial
- cutting
- daily
- diurnal
- ephemeral
- evergreen
- exotic
- fortnightly
- hebdomadal
- hourly
- menstrual
- momentary
- monthly
- perennial
- quarterly
- quincentenary
- quincentennial
- quotidian
- secular
- semestral
- semiannual
- semimonthly
- semiweekly
- tertian
- weekly
- yearly
