| 1 | Middle English | flaske | Alternative form of flask; case, cask, keg |
| 2 | Old English | flasce | flask, bottle |
| 3 | Proto-West Germanic | flaskā | bottle, flask |
| 4 | Proto-Germanic | flaskǭ | a plaiting-covered vessel; bottle, flask |
| 5 | Proto-Germanic | flehtaną | to plait, to weave |
| 6 | Proto-Indo-European | pleḱ- | to fold, plait, weave |
| 7 | Proto-Indo-European | pel- | to cover, to wrap; skin, hide, cloth; to fold |