The Spanish word 'enojo' (meaning 'anger') comes from the Spanish verb 'enojar' ('to anger'), which developed from the Vulgar Latin word 'inodiare' meaning 'to cause hatred.' This Vulgar Latin term was formed by combining two Latin elements: the preposition 'in-' ('in') and the noun 'odium' ('hatred'). The evolution from 'inodiare' to 'enojar' shows how the concept of 'causing hatred' gradually shifted to the more specific meaning of 'causing anger' in Spanish.

Some related Spanish words include the verb form 'enojar' (to anger), 'enojado' (angry), and 'enojón' (quick-tempered). These all share the same root and form a family of words relating to anger and annoyance in Spanish.

While English 'enojo' cognates are not common in everyday speech, the Latin root 'odium' has given English some formal or literary words like 'odious' (hateful, repulsive) and 'odium' itself (strong dislike or contempt). You can see how these English words maintain the original Latin meaning of 'hatred' while the Spanish 'enojo' evolved to specifically mean 'anger.'