The Spanish word 'sesgo' (meaning 'diagonal' or 'bias') has an interesting evolution from Latin roots. It begins with the Latin verb 'sedere' meaning 'to sit', which formed the past participle 'sessus' ('seated'). This evolved into the Vulgar Latin 'sessicare' meaning 'to make sit' or 'to calm down'. The word then transformed into Old Spanish 'sessegar' ('to calm'), before becoming 'sesgar' ('to cut diagonally') in Spanish, and finally the noun/adjective 'sesgo'.

The semantic evolution from 'sitting' to 'diagonal/bias' might seem unusual, but it likely developed through the idea of making something settle or calm down (like sitting), then shifting to the notion of making something slope or lean (like how a seated person leans), and finally to the modern meaning of a diagonal cut or bias.

A common related Spanish word is 'sosegar' (to calm down, to settle), which comes from the same Old Spanish word 'sessegar'. While 'sesgo' developed to describe physical diagonal positions or bias, 'sosegar' retained the original meaning of calming or settling down.

English speakers might recognize the connection to words like 'sedentary', 'sediment', and 'sedate', which all come from the same Latin root 'sedere' (to sit). Just as 'sedentary' refers to sitting or being inactive, and 'sediment' refers to particles that settle or sit at the bottom, 'sesgo' developed from this same concept of settling into its current meaning of a diagonal position or bias.