Pictogram (象形) – originally a serpent with prominent whiskered mouth and eyes.
Current form developed in large seal script, with serpent’s body on right (tail at upper right, legs on right), whiskered/fanged mouth at lower left, and eyes/crown at upper left. Left side was subsequently simplified and abstracted, with some influence of 立 and ⺼/月. Note that 竜 existed as a traditional variant dating back to large seal script, and figures a dragon seen face-on, rather than curled around.
From Proto-Sino-Tibetan*m-bru(ŋ/k)(“dragon; thunder”). Cognate with Tibetanའབྲུག('brug, “dragon; thunder”). The STEDT database also lists 隆 (OC *ɡ·ruːŋ, “thunder; sound of thunder”) and 雹 (OC *bruːɡ, “hail”) as cognates. Also compare 靐 (OC *brɯŋs, “sound of thunder”) and 霹靂 (OC *pʰeːɡ reːɡ, “thunder”).
Kyūjitai; simplified into 竜 as isolated shinjitai kanji, but used in Jōyō characters 襲 and 籠 (latter Jōyō as of 2010).
Although it is officially simplified into 竜, 龍 is often used instead for certain words for its aesthetics (such as in literary contexts or for spelling words borrowed from Chinese). For example, 烏龍茶 is rarely spelled as 烏竜茶.
Coblin, reconstructing the Pai-lang pronunciation as *gljung, suggests that it derives from Proto-Sino-Tibetan*kl(j)u(ŋ/k)(“river, gorge”) and retains its consonant cluster, which was lost in Proto-Lolo-Burmese. Compare Tibetanལྗོངས(ljongs), Chinese谷 (OC *kloːɡ).