The Spanish word 'oscuridad' (meaning 'darkness') comes from the Latin word 'obscuritas', which also meant 'darkness'. This Latin word was derived from 'obscurus' (meaning 'dark'), which was formed by combining two elements: the prefix 'ob-' (meaning 'against' or 'facing') and 'scurus' (meaning 'covered' or 'hidden'). The literal sense was therefore something like 'facing what is hidden' or 'against what is covered', which evolved to mean 'dark' or 'darkness'.

In Spanish, the word developed from 'obscuritas' to 'oscuridad', dropping the 'b' sound and using the common Spanish suffix '-dad' (equivalent to English '-ty' or '-ness') to indicate a quality or state of being.

A simpler and more common related Spanish word is 'oscuro' (meaning 'dark'), which comes directly from Latin 'obscurus'. This is actually the base word to which the suffix '-dad' was added to form 'oscuridad'. Learning 'oscuro' first can make it easier to remember 'oscuridad', as it follows the pattern of adding '-dad' to an adjective to create a noun describing that quality (like 'claro' → 'claridad', 'feliz' → 'felicidad').

English speakers might recognize the connection to the word 'obscure', which comes from the same Latin root 'obscurus'. While 'obscure' in English has evolved to primarily mean 'unclear', 'unknown', or 'hard to understand', you can see how this meaning developed from the original sense of 'dark' or 'hidden'. We also have words like 'obscurity' (from Latin 'obscuritas'), which parallels the Spanish 'oscuridad' in both its formation and original meaning.