Possibly a dialectally-preserved disyllabic form of 角 (jiǎo) (jiǎo, OC *kroːg, "corner; horn"). Unattested in Old Chinese or Middle Chinese literatures, and its usage seems rather recent. Cognate with 角落 (jiǎoluò) (jiǎoluò, OC *kroːg g·raːg, "corner", attested in Classic of Rites), an emphatic form of 角 (jiǎo) (jiǎo, OC *kroːg, "corner; horn"). Many languages exhibit k(V)l- or k(V)r- shapes in roots relating to "corner", "horn" or "crookedness"; compare English corner (< L. cornū(“horn”)), horn (both << PIE *ḱer- ("horn")), Russian угол(úgol, “corner”).
Graphically derived from two different stacking patterns of 日 (rì, “sun”) and 九 (jiǔ, “nine”), with unclear connotations.