ff or ff.

1. Fecerunt (Latin), (they) did it or made it
2. Folios (printing)
3. Following pages, lines, etc
4. Fortissimo (music)

FF

1. Form feed (computing)
2. French franc or francs

• pestling
• pesto
• pestological
• pestologies
• pestologist
• pestologists
• pestology
• pestos
• pests
• pet
• PET
• Pet.
• peta-
• PETA
• Peta
• petaflop
• petaflops
• petal
• petaliferous
• petaline
• petalism
• petalisms
• petalled
• petalodies
• petalody