The Spanish word 'cárcel' (meaning 'prison') comes directly from the Latin word 'carcer', which meant 'prison' or 'enclosure with bars'. This is a straightforward etymology where both the form and meaning have remained remarkably stable over time, with only minor phonetic changes adapting the word to Spanish pronunciation patterns, including the addition of the accent mark over the 'á' to maintain the original stress pattern.

The word 'cárcel' is relatively basic in Spanish and doesn't have many simpler related words in common use. However, you might encounter the adjective 'carcelario' (meaning 'prison-related' or 'penitentiary') and the word 'encarcelar' (meaning 'to imprison'), which are both derived from 'cárcel'.

While English 'prison' comes from a different Latin root, English has borrowed some words from the same Latin 'carcer' root. The most notable is 'incarcerate' (meaning 'to imprison'), which entered English through Medieval Latin 'incarceratus'. The word 'carcer' is also used in some technical contexts, particularly in old astronomical texts where it referred to a confined space or prison house.