sem·i·cen·ten·ni·al 
(sĕm′ē-sĕn-tĕnē-əl, sĕm′ī-)
(sĕm′ē-sĕn-tĕnē-əl, sĕm′ī-)adj.
Marking the 50th anniversary of an event.
n.
A 50th anniversary or its celebration.
- photo-
- photoactive
- photoactivity
- photoaged
- photoaging
- photoautotroph
- photoautotrophic
- photoautotrophically
- photobiologic
- photobiological
- photobiology
- photobomb
- photocell
- photochemical
- photochemically
- photochemical smog
- photochemistry
- photochromatic
- photochromism
- photocoagulate
- photocoagulation
- photocompose
- photocomposition
- photoconduction
- photoconductive