From Proto-Vietic *t-kɛːŋʔ ~ *t-gɛːŋʔ, from Proto-Mon-Khmer *kaŋ ~ *kaaŋ ~ *kaiŋ() ~ *kiəŋ ~ *kaik; cognate with Arem
/kɑːŋˀ/ and Sedang tơkang. The tone correspondence is irregular.
Or Non-Sino-Vietnamese reading of Chinese 梗 (“branch”; SV: ngạnh), but the tonal correspondence to this is also irregular.
The expected tone in both scenarios should be sắc or nặng.
cành • (梗)