| 1 | Middle English | folisch | Foolish, erroneous, ridiculous; Sinful,... |
| 2 | Middle English | fol | Alternative form of fole |
| 3 | Old French | fol | mad; insane; foolish; silly |
| 4 | Latin | follis | bellows; purse, sack, money bag; a small value... |
| 5 | Proto-Indo-European | bʰelǵʰ- | to swell |
| 6 | Proto-Indo-European | bʰel- | to sound; to speak, roar, bark; shiny, white; to... |
| 7 | Proto-Indo-European | bʰōl- | — |