The Spanish verb 'ceñir', meaning 'to gird' or 'to encircle', comes directly from the Latin verb 'cingere', which had the same meaning. This is a straightforward inheritance where both the form and meaning have remained remarkably similar over time. The main changes were phonetic: the Latin 'ci-' evolved into Spanish 'ce-' (both pronounced similarly), and the '-ng-' softened to '-ñ-', which is a common sound change pattern from Latin to Spanish.

A common related Spanish word is 'cintura' (waist), which comes from the same Latin root. Just as 'ceñir' refers to encircling something, 'cintura' refers to the narrowest part of the torso where a belt would traditionally be worn or 'encircle' the body. Another related word is 'cinturón' (belt), which is literally the object used to 'ceñir' or gird oneself.

English speakers might recognize this root in words like 'cincture' (a belt or girdle) and 'cinct' (bound or encircled), though these are rather formal or archaic. More commonly, you might encounter this root in the word 'precinct', which originally referred to an area 'girded' or enclosed by boundaries. The word 'cinch' (meaning an easy task, or to secure something tightly) also comes from this same Latin root, entering English through Spanish 'cincha' (girth strap).