| formidable | Inspiring fear or respect through being impressively large, powerful, intense, or capable | |
| fortitude | Courage in pain or adversity | |
| fortuitous | Happening by accident or chance rather than design | |
| fracas | A noisy disturbance or quarrel | |
| frenetic | Fast and energetic in a rather wild and uncontrolled way | |
| froward | habitually disposed to disobedience and opposition | |
| frugal | Sparing or economical as regards money or food | |
| fruition | The realization or coming into existence of something that was desired or worked for; fulfillment | |
| fudge | A soft, rich confection made with sugar, milk, butter, and flavoring, often chocolate | |
| fulsome | Complimentary or flattering to an excessive degree. | |