| 1 | Middle English | flewme | Phlegm as one of the four cardinal humours... |
| 2 | Old French | fleume | phlegm |
| 3 | Latin | phlegma | phlegm |
| 4 | Ancient Greek | φλέγμα | flame, fire, heat; inflammation; phlegm, a cold... |
| 5 | Ancient Greek | φλέγω | I set on fire, burn, scorch; I kindle, arouse,... |
| 6 | Proto-Indo-European | bʰel- | to sound; to speak, roar, bark; shiny, white; to... |
| 7 | Proto-Indo-European | bʰōl- | — |