- KangXi: page 671, character 10
- Dai Kanwa Jiten: character 19037
- Dae Jaweon: page 1080, character 7
- Hanyu Da Zidian: volume 3, page 2205, character 4
- Unihan data for U+70EF
|simp. and trad.
Phono-semantic compound (形聲): semantic 火 (“fire”) + phonetic 希, the latter being derived from 稀 (xī, “rare”) of which it is the phonetic element. This is coined in light of the observed lack of hydrogens (as compared to alkanes) in alkenes and the fact that alkenes are flammable.