The Spanish word 'suegra' (meaning 'mother-in-law') comes from the Vulgar Latin word 'socra', which itself developed from the Classical Latin 'socrus', also meaning 'mother-in-law'. The evolution from 'socrus' to 'suegra' shows typical sound changes that occurred as Latin evolved into Spanish: the 'o' became 'ue' (a common diphthongization in Spanish), and the consonant cluster was modified to be easier to pronounce, with 'cr' becoming 'gr'.

The word 'suegra' doesn't have many closely related simpler Spanish words, as it comes from a specific Latin term for family relationships. However, Spanish speakers might find it helpful to know that the male counterpart 'suegro' (father-in-law) follows the same pattern, simply changing the ending to indicate masculine gender.

While English 'mother-in-law' isn't directly related to 'suegra', it's interesting to note that both languages created terms for this relationship differently: Spanish inherited the Latin word, while English created a compound word using 'mother' and 'in-law'. There aren't any common English words that derive from the Latin 'socrus', as English typically uses Germanic-based terms for close family relationships.