path·o·gen 
(păthə-jən)
(păthə-jən)n.
An agent that causes disease, especially a virus, bacterium, or fungus.
- Fourierite
- Fourier series
- Fourier transform
- four-in-hand
- four-leaf clover
- four-letter word
- four-o'clock
- four-peat
- fourpenny nail
- fourplex
- four-poster
- fourragère
- fourscore
- foursome
- foursquare
- foursquarely
- four-star
- fourteen
- fourteenth
- fourth
- fourth dimension
- fourth estate
- Fourth of July
- fourth quantum number
- fourth wall