The Spanish verb 'oscurecer' (meaning 'to darken') comes from combining the Spanish adjective 'oscuro' ('dark') with the verb-forming suffix '-ecer', which indicates a gradual change or becoming. The adjective 'oscuro' itself derives from Latin 'obscurus' meaning 'dark' or 'hidden', which was formed by combining the prefix 'ob-' ('against, facing') with 'scurus' ('covered, hidden'). The Latin prefix 'ob-' suggests the idea of something being covered or faced against light, while 'scurus' directly relates to the concept of being hidden from view.

The most common related Spanish word is the adjective 'oscuro' meaning 'dark', which is both simpler and more frequently used than the verb 'oscurecer'. You might also encounter 'oscuridad' (darkness) and 'oscuramente' (darkly), all stemming from the same Latin root 'obscurus'.

English speakers might recognize the connection to words like 'obscure' and 'obscurity', which come from the same Latin root 'obscurus'. While the Spanish word focuses more on literal darkness, the English words tend to be used more figuratively to mean 'unclear', 'hidden from view', or 'not well-known'. This semantic shift from physical darkness to metaphorical unclear or hidden meaning occurred in English, while Spanish retained both literal and figurative uses.