| extracurricular(fickle, untrustworthy, unprincipled, dirty-dealing) |
| eyewash(cheat, ripoff, treachery) |
| fair-weather(fickle, untrustworthy, unprincipled) |
| faithless(fickle, untrustworthy, unprincipled, dirty-dealing) |
| fakery(cheat, ripoff, treachery) |
| false-heartedness(treachery, deceit, disloyalty) |
| falsehearted(fickle, untrustworthy, unprincipled, dirty-dealing) |
| falsity(treachery, deceit, disloyalty) |
| fast one(expression, cheat, ripoff, treachery, dissimulation) |
| feint(deception, dishonesty, treachery) |
| fickle(untrustworthy, unprincipled, dirty-dealing) |
| fickleness(treachery, deceit, disloyalty) |
| fishy(adjective, wrong, immoral) |
| flam(cheat, ripoff, treachery, collusion) |
| fly-by-night(adjective, wrong, immoral) |
| fly by night(expression, idiom, fickle, untrustworthy, unprincipled) |
| foresworn(fickle, untrustworthy, unprincipled, dirty-dealing) |
| four-flusher(cheat, ripoff, treachery) |
| fourberie(cheat, ripoff, treachery) |
| foxiness(cunning, craftiness, wiles) |