The Spanish word 'cónyuge' (meaning 'spouse') comes from the Latin word 'coniux', which also meant 'spouse'. The Latin term was formed by combining two elements: the prefix 'con-' meaning 'together' and 'iugum' meaning 'yoke'. This etymology reflects the ancient concept of marriage as two people being 'yoked together' or joined in union. The metaphor of a yoke, which was used to join two draft animals together for working, provided a powerful image for the marriage bond in ancient Roman culture.

A related Spanish word is 'yugo', which directly comes from Latin 'iugum' and still means 'yoke'. The connection between 'cónyuge' and 'yugo' reflects the original metaphor of marriage as a joining or yoking together of two people. Another related term is 'conyugal' (conjugal), which refers to things relating to marriage.

Several English words share this ancient root, including 'conjugal' (relating to marriage), which is very close in form and meaning to Spanish 'conyugal'. The word 'subjugate' (to bring under control) also contains the Latin root 'iugum', literally meaning to 'place under the yoke'. Even the word 'join' is distantly related, coming from the same Indo-European root that gave us Latin 'iugum'.