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

• mainstream
• mainstreamed
• mainstreaming
• main streams
• mainstreams
• Main Street
• mainstreeting
• mainstreetings
• maintain
• maintainabilities
• maintainability
• maintainable
• maintain capital intact
• maintained
• maintainer
• maintainers
• maintaining
• maintains
• maintenance
• maintenanced
• maintenance-man
• maintenance-men
• maintenances
• maintenancing
• maintop