| Word | Reading | Meaning |
| 蛍 | ほたる, ホタル | firefly, lightning bug |
| 蛍光灯 | けいこうとう | fluorescent lamp, fluorescent light; person who is slow to react, someone slow on the uptake |
| 蛍光 | けいこう | fluorescence |
| 蛍光塗料 | けいこうとりょう | fluorescent paint |
| 蛍光物質 | けいこうぶっしつ | fluorescent substance, phosphor |
| 蛍狩り | ほたるがり | firefly catching |
| 蛍雪の功 | けいせつのこう | the fruit of diligent study |
| 蛍火 | けいか, ほたるび | light of a firefly |
| 蛍光燈 | けいこうとう | fluorescent lamp, fluorescent light; person who is slow to react, someone slow on the uptake |
| 蛍烏賊 | ほたるいか, ホタルイカ | firefly squid (Watasenia scintillans), sparkling enope squid |